CN114823951A - Solar cell and photovoltaic module - Google Patents

Solar cell and photovoltaic module Download PDF

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CN114823951A
CN114823951A CN202210738558.4A CN202210738558A CN114823951A CN 114823951 A CN114823951 A CN 114823951A CN 202210738558 A CN202210738558 A CN 202210738558A CN 114823951 A CN114823951 A CN 114823951A
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substrate
solar cell
width
back surface
area
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金井升
张彼克
张昕宇
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Jinko Solar Haining Co Ltd
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Jinko Solar Haining Co Ltd
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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
    • H01L31/0248—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 characterised by their semiconductor bodies
    • H01L31/0352—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 characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
    • H01L31/035272—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 characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions characterised by at least one potential jump barrier or surface barrier
    • H01L31/035281—Shape of the body
    • 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
    • H01L31/0216—Coatings
    • H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/02167—Coatings for devices characterised by at least one potential jump barrier or surface barrier for 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
    • H01L31/022441—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
    • H01L31/04—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
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
    • H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
    • 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
    • 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
    • H01L31/186—Particular post-treatment for the devices, e.g. annealing, impurity gettering, short-circuit elimination, recrystallisation
    • H01L31/1868—Passivation

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Abstract

The embodiment of the application relates to the photovoltaic field, and provides a solar cell and a photovoltaic module, wherein the solar cell comprises: the substrate is provided with a front surface and a back surface which are opposite, the back surface comprises a first area and a second area adjacent to the first area, the substrate of the first area is internally provided with a doping element, and the doping element is N-type or P-type; along a first direction, the width of a first protruding structure of the first area is smaller than that of a second protruding structure of the second area, the first protruding structure comprises a platform protruding structure, and the top surface of the platform protruding structure is a polygonal plane; the tunneling dielectric layer is positioned on the back surface of the substrate; the doped conducting layer is positioned on the surface of the tunneling dielectric layer, and the type of doped elements in the doped conducting layer is the same as that in the first region; the back electrodes are arranged along the first direction, correspond to the substrate of the first area and are in contact with the doped conducting layer, and the photoelectric conversion efficiency of the solar cell can be at least improved.

Description

Solar cell and photovoltaic module
Technical Field
The embodiment of the application relates to the field of photovoltaics, in particular to a solar cell and a photovoltaic module.
Background
The causes affecting the performance of the solar cell (e.g., photoelectric conversion efficiency) include optical loss including reflection loss of the front surface of the cell, shadow loss of contact grid lines, non-absorption loss of long wavelength band, and the like, and electrical loss including loss of photogenerated carrier recombination on the surface and in the body of the semiconductor, contact resistance of the semiconductor and the metal grid lines, contact resistance of the metal and the semiconductor, and the like.
In order to reduce the electrical loss and the optical loss of the solar cell, a polishing process is generally required for the back surface of the solar cell. The back polishing process mainly utilizes a wet chemical method to polish the boron-doped pyramid textured structure on the back, so that the internal reflection of light is increased, the surface recombination rate of a current carrier is reduced, and the photoelectric conversion efficiency of the battery is improved. In the back polishing process, the shape of the polished back surface of the crystalline silicon cell is beneficial to back reflection of long-wave band light and uniformity of a film layer formed on the back surface subsequently, and the crystalline silicon cell has an important effect on improving the efficiency of the solar cell. The back polishing process can optimize the performance of the solar cell, but factors influencing the performance of the solar cell are still more, and the development of the efficient passivated contact solar cell has important significance.
Disclosure of Invention
The embodiment of the application provides a solar cell and a photovoltaic module, which at least facilitate the promotion of the photoelectric conversion efficiency of the solar cell.
According to some embodiments of the present application, there is provided in one aspect a solar cell including: the substrate is provided with a front surface and a back surface which are opposite, the back surface comprises a first area and a second area adjacent to the first area, the substrate of the first area is internally provided with a doping element, and the doping element is N-type or P-type; along a first direction, the width of a first protruding structure of the first area is smaller than that of a second protruding structure of the second area, the first protruding structure comprises a platform protruding structure, and the top surface of the platform protruding structure is a polygonal plane; the tunneling dielectric layer is positioned on the back surface of the substrate; the doped conducting layer is positioned on the surface, far away from the back surface of the substrate, of the tunneling dielectric layer and is provided with doping elements, and the types of the doping elements in the doped conducting layer are the same as those in the first region; the back electrodes are arranged along the first direction, correspond to the substrate of the first area and are in contact with the doped conducting layer.
In addition, along the first direction, the substrate width of the first area is greater than or equal to the width of the back electrode; the substrate of the first region comprises at least one first protruding structure.
In addition, the number of the first protruding structures is two; along the first direction, the distance between the adjacent first protruding structures ranges from 0.1 μm to 10 μm.
In addition, the width of the bottom surface of the first protruding structure is smaller than that of the second protruding structure.
In addition, the width of the top surface of the first protruding structure is smaller than that of the top surface of the second protruding structure.
In addition, the width of the top surface of the first protruding structure is smaller than that of the second protruding structure.
In addition, the height difference between the top surface of the first bump structure and the back surface of the substrate is less than or equal to the height difference between the top surface of the second bump structure and the back surface of the substrate.
In addition, the height difference between the top surface of the first protrusion structure and the back surface of the substrate is 200 nm-500 nm.
In addition, the first region further comprises third protruding structures, and the third protruding structures and the first protruding structures are arranged at intervals along the first direction.
In addition, under the same back electrode, the total width of the cross section of the first protruding structure contacting with the back surface is larger than or equal to the total width of the cross section of the third protruding structure contacting with the back surface.
In addition, the ratio of the total width of the cross section of the first protruding structure in contact with the back surface to the total width of the cross section of the third protruding structure in contact with the back surface ranges from 1:1 to 4: 1.
In addition, the width of the first protruding structure is smaller than that of the third protruding structure.
In addition, the height difference between the top surface of the first protruding structure and the back surface of the substrate is less than or equal to the height difference between the top surface of the third protruding structure and the back surface of the substrate.
According to some embodiments of the present application, there is provided in another aspect a photovoltaic module including: at least one battery string formed by connecting a plurality of solar cells according to any one of the above; the packaging adhesive film is used for covering the surface of the battery string; and the cover plate is used for covering the surface of the packaging adhesive film, which is deviated from the battery string.
The technical scheme provided by the embodiment of the application has at least the following advantages:
in the technical scheme provided by the embodiment of the application, the back surface of the substrate comprises a first area and a second area adjacent to the first area, the substrate of the first area is provided with a doping element, the back electrode corresponds to the substrate of the first area, the substrate of the first area is provided with a first protruding structure, and the first protruding structure is beneficial to reducing the contact resistivity of the back surface of the solar cell and integrally improving the cell efficiency. The width of the first protruding structure of the first area is smaller than that of the second protruding structure of the second area, and the number of the first protruding structures with smaller widths is larger in unit area, so that the total area of the top surface of the formed first protruding structure is larger, and the area contacted by the back electrode is the first area, thereby being beneficial to reducing contact resistance. The conventional tunneling dielectric layer and the doped conducting layer are formed in the first area and the second area of the substrate, the back electrode is in direct contact with the doped conducting layer, the passivation effect is good, carrier recombination on the back surface is reduced, and the utilization rate of light is improved.
Drawings
One or more embodiments are illustrated by the accompanying drawings in the drawings, which correspond to and are not to be construed as limiting the embodiments, unless expressly stated otherwise, the drawings are not to scale. One or more embodiments are illustrated by the accompanying drawings in the drawings, which correspond to the figures in the drawings, and the illustrations are not to be construed as limiting the embodiments, unless otherwise specified, and the drawings are not to scale; in order to more clearly illustrate the embodiments of the present application or technical solutions in the conventional technology, the drawings needed to be used in the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a solar cell according to an embodiment of the present disclosure;
fig. 2 is a schematic partial structure diagram of a solar cell according to an embodiment of the present disclosure;
fig. 3 is a schematic partial structure diagram of another solar cell according to an embodiment of the present disclosure;
fig. 4 is a schematic view of another partial structure of a solar cell according to an embodiment of the present disclosure;
fig. 5 is a schematic structural diagram of a photovoltaic module according to an embodiment of the present disclosure;
fig. 6 is a schematic structural diagram of a substrate provided in a method for manufacturing a solar cell according to an embodiment of the present disclosure;
fig. 7 is a schematic structural diagram of an initial textured structure formed in a solar cell manufacturing method according to an embodiment of the present disclosure;
fig. 8 is a schematic structural diagram illustrating a backside of a substrate formed in a method for fabricating a solar cell according to an embodiment of the present disclosure;
fig. 9 is a schematic structural diagram illustrating another method for forming a backside of a substrate in a method for fabricating a solar cell according to an embodiment of the present disclosure;
fig. 10 is another schematic structural diagram of an initial textured structure formed in a solar cell manufacturing method according to an embodiment of the present disclosure;
fig. 11 is a schematic view of another structure for forming the backside of the substrate in the method for manufacturing a solar cell according to an embodiment of the present disclosure;
fig. 12 is a schematic view of another structure for forming the backside of the substrate in the method for manufacturing a solar cell according to an embodiment of the present disclosure;
fig. 13 is a schematic structural diagram illustrating a first bump structure formed in a solar cell manufacturing method according to an embodiment of the present disclosure;
fig. 14 is a schematic structural diagram illustrating formation of a tunneling dielectric layer in a solar cell manufacturing method according to an embodiment of the present disclosure;
fig. 15 is a schematic structural diagram illustrating a doped conductive layer formed in a solar cell manufacturing method according to an embodiment of the present disclosure;
fig. 16 is a schematic structural diagram illustrating a passivation layer formed in a solar cell manufacturing method according to an embodiment of the present disclosure;
fig. 17 is a schematic structural diagram of a back electrode formed in a solar cell manufacturing method according to an embodiment of the present disclosure.
Detailed Description
As is clear from the background art, the photoelectric conversion efficiency of the solar cell in the prior art is not good enough.
Analysis finds that one of the reasons for poor photoelectric conversion efficiency of the solar cell is that the existing process generally performs polishing treatment on a textured structure on the back surface of the solar cell after texturing the solar cell, so that the back reflection of the cell on long-wave band light and the uniformity of a subsequent back film of the cell are improved, the carrier recombination on the back surface is reduced, and the utilization rate of light is improved. However, after the back surface is polished, the doped conductive layer formed subsequently is difficult to match with the back metal electrode, so that good ohmic contact cannot be formed, the contact resistivity of the doped conductive layer is high, and the contact resistance between the back electrode and the doped conductive layer is high, which affects the improvement of the efficiency of the solar cell.
The embodiment of the application provides a solar cell, through forming first protruding structure in the just right region (first district) of back electrode, form second protruding structure in the not just right region (second district) of back electrode, the width of first protruding structure is less than the width of the protruding structure of second, the contact resistance of back electrode is controlled through the ratio of the area of contact of back electrode and first protruding structure and the sectional area of back electrode self in the control unit area, and the basement back has first protruding structure, can form good ohmic contact between doping conducting layer and the back electrode, reduce the contact resistance between doping conducting layer and the back electrode, thereby promote solar cell efficiency. The width of the second protruding structure is larger, so that the subsequent deposition and uniformity of a film layer formed on the top surface of the second protruding structure are facilitated, a good passivation effect is provided, and the carrier recombination on the back surface is reduced.
Embodiments of the present application will be described in detail below with reference to the accompanying drawings. However, it will be appreciated by those of ordinary skill in the art that in the examples of the present application, numerous technical details are set forth in order to provide a better understanding of the present application. However, the technical solution claimed in the present application can be implemented without these technical details and various changes and modifications based on the following embodiments.
Fig. 1 is a schematic structural diagram of a solar cell according to an embodiment of the present disclosure; fig. 2 is a schematic partial structure diagram of a solar cell according to an embodiment of the present disclosure; fig. 3 is a schematic partial structure diagram of another solar cell according to an embodiment of the present disclosure; fig. 4 is a schematic view of another partial structure of a solar cell according to an embodiment of the present disclosure.
Referring to fig. 1 to 4, an aspect of the present disclosure provides a solar cell, including: the semiconductor device comprises a substrate 100, wherein the substrate 100 is provided with a front surface 101 and a back surface 102 which are opposite to each other, the back surface 102 comprises a first region 103 and a second region 104 which is adjacent to the first region 103, and the substrate 100 of the first region 103 is internally provided with a doping element which is N-type or P-type; along the first direction X, the width of the first raised structures 111 of the first region 103 is smaller than the width of the second raised structures 112 of the second region 104; tunnel dielectric layer 121, tunnel dielectric layer 121 is located on back surface 102 of substrate 100; a doped conductive layer 122, wherein the doped conductive layer 122 is located on the surface of the tunnel dielectric layer 121 far from the back surface 102 of the substrate 100, the doped conductive layer 122 has a doping element, and the type of the doping element in the doped conductive layer 122 is the same as the type of the doping element in the first region 103; the back electrode 131, the back electrode 131 is arranged along the first direction X, the back electrode 131 corresponds to the substrate 100 of the first region 103, and the back electrode 131 is in contact with the doped conductive layer 122.
In some embodiments, the solar cell is a Tunnel Oxide Passivated Contact (TOPCon) cell, which may include a double-sided Tunnel Oxide Passivated Contact cell or a single-sided Tunnel Oxide Passivated Contact cell. Illustratively, the solar cell is a single-sided tunnel oxide passivation contact cell, and the back side of the solar cell has a tunnel oxide passivation layer.
The substrate 100 is a region that absorbs incident photons to generate photogenerated carriers. In some embodiments, the substrate 100 is a silicon substrate 100, which may include one or more of single crystal silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In other embodiments, the material of the substrate 100 may also be silicon carbide, an organic material, or a multi-component compound. The multi-component compound may include, but is not limited to, perovskite, gallium arsenide, cadmium telluride, copper indium selenide, and like materials. Illustratively, the substrate 100 in the embodiment of the present application is a single crystal silicon substrate.
In some embodiments, the front surface 101 of the substrate 100 is a light-receiving surface to absorb incident light, and the back surface 102 of the substrate 100 is a backlight surface. The substrate 100 has therein a doping element, which may be N-type or P-type, the N-type element may be a group v element such As a phosphorus (P) element, a bismuth (Bi) element, an antimony (Sb) element, or an arsenic (As) element, and the P-type element may be a group iii element such As a boron (B) element, an aluminum (Al) element, a gallium (Ga) element, or an indium (In) element. For example, when the substrate 100 is a P-type substrate, the type of the doped element therein is P-type. For another example, when the substrate 100 is an N-type substrate, the type of the doped element therein is N-type.
In some embodiments, the position of the first region 103 corresponds to the position of the back electrode 131 in the front projection of the substrate, and the substrate 100 of the first region 103 may be a heavily doped region, i.e., the doping concentration of the substrate 100 of the first region 103 is greater than that of the substrate of the second region 104. Thus, the region directly opposite to the back electrode 131 is a heavily doped region, which reduces the contact resistance between the back electrode 131 and the substrate 100, and the doped ions can be used as carriers, thereby increasing the number of carriers and the mobility of the carriers, and facilitating the improvement of the photoelectric conversion efficiency of the solar cell. The substrate 100 of the second region 104 is a lightly doped region, which reduces the recombination rate on the substrate surface and improves the photoelectric conversion efficiency of the cell.
The substrate 100 of the first region 103 and the substrate 100 of the second region 104 may be regions of the back surface 102 of the substrate 100 after being subjected to a back surface polishing process, wherein the substrate 100 of the first region 103 is subjected to local laser texturing before being subjected to the back surface polishing process, and the height and the width of a formed textured structure are both smaller than those of the textured structure on the surface of the second region 104, so that when the back surface polishing process is performed, the same reaction time and reaction temperature are used, and the first region and the second region with different textured structures are finally formed. In some embodiments, the width of the substrate 100 of the first region 103 is greater than or equal to the width of the back electrode 131 along the first direction X. The area contacted by the back electrode 131 is the substrate 100 of the first region 103, which is beneficial to reducing the contact resistance. However, it is understood that the width of the substrate 100 of the first region 103 should not be too large, and the too large width of the substrate 100 of the first region 103 may affect the film integrity and uniformity of the surface of the substrate 100 of the second region 104, and reduce the internal reflection of light, thereby not contributing to the improvement of the carrier surface recombination rate and the photoelectric conversion efficiency of the solar cell. Meanwhile, the interface passivation effect of the passivation contact structure constructed by the tunneling dielectric layer 121 and the doped conductive layer 122 is affected, so that the Jo load current is higher and the surface recombination rate of carriers is reduced. Further, the width of the substrate 100 of the first region 103 is 20 μm to 50 μm. Specifically, it may be 20.3. mu.m, 33. mu.m, 35. mu.m, 45. mu.m or 49. mu.m.
In some embodiments, the extending direction of the first region 103 is the same as the extending direction of the back electrode 131, and the extending length of the first region 103 corresponds to the extending length of the back electrode 131. Therefore, the first protruding structures 111 of the first region 103 can increase the lateral transmission of the cell, reduce the lateral transmission loss of the cell, and improve the photoelectric conversion efficiency of the solar cell. In other embodiments, the back surface includes a plurality of first regions arranged along a second direction (a direction in which the back electrode extends); the distance range between the adjacent first regions is 10 mm-20 mm, so that the carrier recombination rate is reduced, the passivation effect of the formed passivation contact structure is better, and the open-circuit voltage Voc and the fill factor FF can be improved. The spacing between adjacent first regions 103 may specifically be 10.3mm, 13mm, 15.1mm, 17mm or 19 mm.
In some embodiments, the substrate 100 of the first region 103 includes at least one first protrusion structure 111 on the same back electrode 131, and the plurality of first protrusion structures 111 are arranged at intervals along the first direction X. As shown in fig. 1 and 3, the number of the first protrusion structures 111 is two; in the first direction X, the range of the distance S between the adjacent first protruding structures 111 is 0.1-10 μm; further, the spacing S between adjacent first bump structures 111 ranges from 0.5 μm to 5 μm, and the spacing S between the first bump structures 111 may be 0.8 μm, 1 μm, 1.9 μm, 2.8 μm, or 4.6 μm. The distance between the adjacent protruding structures can ensure that incident light is reflected for multiple times between the adjacent protruding structures, and the optical path of the incident light is prolonged, so that absorption of long-wave band photons is facilitated. In addition, the distance between the adjacent first protruding structures 111 is smaller, and the width of the first protruding structures 111 is also smaller, so that the number of the first protruding structures 111 in the first region 103 of the substrate 100 per unit area is larger, and the total area of the back electrode 131 contacting the first protruding structures 111 is increased, thereby reducing the contact resistance. The distance between the adjacent first protruding structures 111 should not be too small, so that the first protruding structures 111 on the surface of the substrate 100 are too close to increase the specific surface area of the substrate 100, and further, the number of defect sites on the surface of the substrate 100 increases, so that the passivation effect of the solar cell decreases, and the photoelectric conversion efficiency of the solar cell is affected.
In some embodiments, referring to FIG. 2, the width W of the bottom surface of the first raised structure 111 1 Is less than the bottom surface width L of the second protrusion structure 112 1 . Top surface width W of first bump structure 111 2 Is less than the width L of the top surface of the second bump structure 112 2 It can be naturally deduced that the size of the first bump structure 111 is smaller than that of the second bump structure 112, and the smaller size of the first bump structure 111 has high reflectivity and high short-circuit current; the second protrusion structure 112 with a larger size is beneficial to deposition and passivation of the formed tunneling dielectric layer and the doped conductive layer film layer, and is beneficial to improvement of the open-circuit voltage and the short-circuit current of the solar cell, so that the cell efficiency is improved. Specifically, the bottom surface width W of the first bump structure 111 1 The range is 2 μm to 2.8 μm, W 1 Specifically, it may be 2.1. mu.m, 2.3. mu.m, 2.6. mu.m, or 2.8. mu.m. Top surface width W of first bump structure 111 2 In the range of 1 μm to 2 μm, W 2 Specifically, it may be 1.03. mu.m, 1.4. mu.m, 1.8. mu.m, or 2 μm. Bottom surface width L of second bump structure 112 1 The range is 7 μm to 9 μm, L 1 Specifically, it may be 7.3. mu.m, 7.8. mu.m, 8.3. mu.m, or 8.8. mu.m. Top surface width L of second bump structure 112 2 The range of 5 to 7 μm, L 2 Specifically, it may be 5.3. mu.m, 5.6. mu.m, 6.5. mu.m, or 6.9. mu.m.
In some embodiments, the height difference H between the top surface of the first bump structure 111 and the back surface of the substrate 1 Not more than the height difference H between the top surface of the second bump structure 112 and the back surface of the substrate 2 . The light incident on the inclined surface of the first raised structure 111 may be reflected again to the inclined surface of the second raised structure 112 higher to form multiple absorption, increasing the absorption of long-band photons.
In some embodiments, the height difference H of the top surface of the first raised structure 111 from the back surface 102 of the substrate 100 1 200nm to 500nm, H 1 Specifically, the light may be 230nm, 260nm, 350nm, 459nm, or 498nm, and by using the light trapping effect of the first protrusion structure 111 and the height difference between the top surface of the first protrusion structure 111 and the back surface 102 of the substrate 100, the light is incident on the inclined surface of the first protrusion structure 111 and then reflected to the inclined surface of another protrusion structure (the first protrusion structure 111, the second protrusion structure 112, or the third protrusion structure) to form multiple absorption. The incident light is reflected for multiple times, the advancing direction of the incident light in the solar cell is changed, the optical path is prolonged, and the absorption of long-wave band photons is increased. Similarly, the height difference H between the top surface of the second bump structure 112 and the back surface 102 of the substrate 100 2 400nm to 700nm, H 2 Specifically, the wavelength may be 460nm, 530nm, 590nm, 631nm, or 689 nm.
In some embodiments, the first raised structure 111 comprises a plateau raised structure, the top surface of which is a polygonal plane. In the conventional design, the texture structure is generally a pyramid structure or the back surface of the texture structure is in a polished surface shape, but the top of the pyramid structure is in a point structure, so that the surface area is small, the deposition of a subsequently formed film layer is not facilitated, and the passivation effect is influenced; the polished surface has a high reflectance of light on one side and the contact resistance between the substrate and the electrode is too high, thereby affecting the cell efficiency. The side surfaces of the platform protruding structures form included angles with the surface of the substrate, and incident light can be reflected from any platform protruding structure to the other platform protruding structure, so that the reflection reducing effect of a suede formed by the platform protruding structures is good, namely the reflectivity of light is reduced, the short-circuit current Isc is improved, and the photoelectric conversion efficiency of the battery is improved; the top surface of the raised structure of the platform is a polygonal plane, so that the subsequent film layer is easy to deposit, the defects of the subsequently formed film layer are fewer, and the passivation effect of the solar cell is improved. In other embodiments, the first raised structure 111 comprises a plateau-like raised structure or other raised structure having a sloped surface and a top surface. Similarly, the second bump structure 112 includes a mesa bump structure, a mesa-like bump structure, or other bump structure having a slope and a top surface. The polygonal plane may be a quadrilateral plane, a pentagonal plane, or a plane of any shape, and the polygonal plane may be a plane of a regular shape or a plane of an irregular shape.
In some embodiments, as shown in fig. 1 and fig. 4, the first region 103 further includes a third protrusion structure 113, and the third protrusion structure 113 is spaced apart from the first protrusion structure 111 along the first direction X. That is, the region opposite to the back electrode 131 includes the first protrusion structure 111 and the third protrusion structure 113, and the width of the first protrusion structure 111 is smaller than the width of the third protrusion structure 113. The suede of the first protrusion structure 111 has the advantages of low reflectivity and high short-circuit current and is used for reducing contact resistance, and the suede of the third protrusion structure 113 has the advantages of good contact with a back electrode and high welding tension and is used for ensuring passivation effect and reducing carrier recombination on the back.
In some embodiments, the width of the third protruding structure 113 may be equal to the width of the second protruding structure 112, and specifically may be the top surface width O of the third protruding structure 113 2 May be equal to the width L of the top surface of the second bump structure 112 2 Equal, bottom width O of the third bump structure 113 1 May be equal to the width L of the bottom surface of the second bump structure 112 1 Are equal. In other embodiments, the third bump structureThe width of 113 is between the width of the first protruding structure 111 and the width of the second protruding structure 112.
In some embodiments, under the same back electrode 131, the total width of the cross section of the first protruding structure 111 contacting the back surface 102 is greater than or equal to the total width of the cross section of the third protruding structure 113 contacting the back surface 102. Specifically, the ratio of the total width of the cross section of the first protruding structure 111 contacting the back surface to the total width of the cross section of the third protruding structure 113 contacting the back surface is 1: 1-4: 1, and further, the ratio of the total width of the cross section of the first protruding structure 111 contacting the back surface to the total width of the cross section of the third protruding structure 113 contacting the back surface is 1: 1-3: 1, which may be 1:1, 1.5:1, 2:1, or 2.8: 1. The third protrusion structures 113 occupy too much, which may affect the back reflection of the solar cell to the long-wavelength light, and further affect the cell efficiency.
In some embodiments, the height difference H between the top surface of the first bump structure 111 and the back surface 102 of the substrate 100 1 Less than or equal to the height difference H between the top surface of the third bump structure 113 and the back surface 102 of the substrate 100 3 . The third bump structure 113 includes a platform bump structure, a platform-like bump structure, or other bump structures with slopes and top surfaces, and the first bump structure 111 includes a platform bump structure, a platform-like bump structure, or other bump structures with slopes and top surfaces.
In some embodiments, in a direction from the back surface 102 to the front surface 101, the first protrusion structure 111 includes a first doping layer and a second doping layer, a doping concentration of the first doping layer is greater than a doping concentration of the second doping layer, and the doping concentration of the first doping layer is greater, which is beneficial to improving a carrier transport efficiency, and is beneficial to improving an open-circuit voltage and a current transmission efficiency, so as to be beneficial to improving a photoelectric conversion efficiency of the solar cell. The doping concentration of the first doping layer comprises 2E 20 cm -3 ~2E 21 cm -3 。
In some embodiments, the doping concentration of the first doping layer is equal to or greater than the doping concentration of the doped conductive layer 122. Therefore, the recombination loss between the tunneling dielectric layer 121 and the first protruding structure 111, and between the first protruding structure 111 and the doped conductive layer 122 can be reduced, which is beneficial to improving the transport efficiency of carriers, and the transport efficiency of open-circuit voltage and current, thereby being beneficial to improving the photoelectric conversion efficiency of the solar cell. In addition, the doping concentration of the first protrusion structure 111 is greater than that of the doped conductive layer 122, which can further reduce the contact resistance of the back electrode 131 to improve the photoelectric conversion efficiency. In other embodiments, the back electrode 131 may directly contact with the first doping layer of the first protrusion structure 111, so as to form a good ohmic contact, and at the same time, a transmission path of current is reduced, which is beneficial to improving the efficiency of the battery.
In some embodiments, the depth of the first doping layer is 1.5% to 4% of the height of the first protrusion structure 111, preferably, the depth of the first doping layer is 90nm to 200nm, and specifically, may be 90nm, 130nm, 160nm, 178nm, or 193 nm. The doping depth of the first doping layer can avoid the tunneling effect caused by the high doping of the first doping layer, that is, the doping elements of the first doping layer cannot diffuse into the surface of the substrate 100 in contact with the emitter 110 or the emitter 110, so that the open-circuit voltage of the solar cell can be increased, and the photoelectric conversion efficiency of the solar cell can be improved.
In some embodiments, the material of tunnel dielectric layer 121 may include, but is not limited to, aluminum oxide, silicon nitride, silicon oxynitride, intrinsic amorphous silicon, intrinsic polysilicon, and other dielectric materials having a tunneling effect. The thickness of tunneling dielectric layer 121 may be 0.5nm to 2.5nm, optionally, the thickness of tunneling dielectric layer 121 is 0.5nm to 2nm, and further, the thickness of tunneling dielectric layer 121 is 0.5nm to 1.2 nm. The material of the doped conductive layer 122 may be at least one of a polycrystalline semiconductor, an amorphous semiconductor, or a microcrystalline semiconductor, and preferably, the material of the doped conductive layer 122 includes at least one of polycrystalline silicon, amorphous silicon, or microcrystalline silicon. The thickness range of the doped conductive layer 122 is 40nm to 150nm, optionally, the thickness range of the doped conductive layer 122 is 60nm to 90nm, and the thickness range of the doped conductive layer 122 can ensure that the optical loss of the doped conductive layer 122 is small and the interface passivation effect of the tunneling dielectric layer 121 is good, so that the battery efficiency is improved. Illustratively, the material of the doped conductive layer 122 in the embodiment of the present application is polysilicon, and the thickness of the doped conductive layer 122 is 80 nm.
In some embodiments, the passivation layer 123 is located on the surface of the doped conductive layer 122, and the passivation layer 123 may be regarded as a post-passivation layer. The passivation layer 123 may have a single-layer structure or a stacked-layer structure, and the material of the passivation layer 123 may be one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbonitride, titanium oxide, hafnium oxide, or aluminum oxide.
The back electrode 131 is a grid line of the solar cell for collecting and collecting the current of the solar cell. The back electrode 131 may be sintered from a fire-through type paste. The material of the back electrode 131 may be one or more of aluminum, silver, gold, nickel, molybdenum, or copper. In some cases, the back electrode 131 refers to a fine gate line or a finger gate line to distinguish from a main gate line or a bus bar.
In some embodiments, the solar cell further comprises: a first passivation layer 124, wherein the first passivation layer 124 is located on the surface of the emitter 110 away from the substrate 100, and the first passivation layer 124 is regarded as a front passivation layer; a plurality of spaced electrodes 132, and the electrodes 132 penetrate the first passivation layer 124 and contact the emitter 110.
In some embodiments, the first passivation layer 124 may have a single-layer structure or a stacked-layer structure, and the material of the first passivation layer 124 may be one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbonitride, titanium oxide, hafnium oxide, or aluminum oxide.
The electrode 132 may be sintered from a fire-through slurry. The contact of the electrode 132 with the emitter 110 may be a local contact or a full contact. The material of the electrode 132 may be one or more of aluminum, silver, nickel, gold, molybdenum, or copper. In some embodiments, the electrode 132 is a top or front electrode. In some cases, the electrode 132 refers to a fine gate line or a finger gate line to distinguish it from a main gate line or a bus bar.
In the solar cell provided in the embodiment of the application, the back surface 102 of the substrate 100 includes a first region 103 and a second region 104 adjacent to the first region 103, the substrate 100 of the first region 103 has a doping element, the back electrode 131 corresponds to the substrate 100 of the first region 103, the substrate 100 of the first region 103 has a first protrusion structure 111, and the first protrusion structure 111 is beneficial to reducing the contact resistivity of the back surface of the solar cell, thereby improving the cell efficiency as a whole. The width of the first protruding structures 111 of the first region 103 is smaller than the width of the second protruding structures 112 of the second region 104, and the number of the first protruding structures 111 with smaller widths in a unit area is larger, so that the total area of the top surfaces of the formed first protruding structures 111 is larger, and the contact areas of the back electrodes 131 are the first regions 103, which is beneficial to reducing the contact resistance. A conventional tunnel dielectric layer 121 and a doped conductive layer 122 are formed in both the first region 103 and the second region 104 of the substrate 100, and the back electrode 131 is in direct contact with the doped conductive layer 122, so that the passivation effect is good, and simultaneously the carrier recombination on the back surface is reduced and the light utilization rate is improved.
Fig. 5 is a schematic structural diagram of a photovoltaic module according to an embodiment of the present disclosure.
Accordingly, referring to fig. 5, another aspect of the embodiments of the present application further provides a photovoltaic module, which is configured to convert received light energy into electrical energy and transmit the electrical energy to an external load. The photovoltaic module includes: at least one cell string formed by connecting a plurality of solar cells 10 (for example, any one of fig. 1 to 4); a packaging adhesive film 21 for covering the surface of the battery string; and the cover plate 22 is used for covering the surface of the packaging adhesive film 21, which faces away from the battery string.
The packaging adhesive film 21 may be an organic packaging adhesive film such as EVA or POE, and the packaging adhesive film 21 covers the surface of the battery string to seal and protect the battery string. In some embodiments, the packaging adhesive films 21 include an upper packaging adhesive film and a lower packaging adhesive film respectively covering both sides of the surface of the battery string. The cover plate 22 may be a cover plate such as a glass cover plate or a plastic cover plate for protecting the battery string, and the cover plate 22 covers the surface of the packaging adhesive film 21 facing away from the battery string. In some embodiments, the cover plate 22 is provided with a light trapping structure to increase the utilization rate of incident light. The photovoltaic module has higher current collection capability and lower carrier recombination rate, and can realize higher photoelectric conversion efficiency. In some embodiments, the cover plates 22 include upper and lower cover plates on both sides of the battery string.
Accordingly, another aspect of the embodiments of the present application provides a method for manufacturing a solar cell, which is used for manufacturing the solar cell provided in the above embodiments (fig. 1 to 4). Details of the same or similar contents or elements as those of the description given in the above embodiment are not repeated, and only a description different from the above description is described in detail. Fig. 6 is a schematic structural diagram of a substrate provided in a method for manufacturing a solar cell according to an embodiment of the present disclosure; fig. 7 is a schematic structural diagram of an initial textured structure formed in a solar cell manufacturing method according to an embodiment of the present disclosure; fig. 8 is a schematic structural diagram illustrating a backside of a substrate formed in a method for fabricating a solar cell according to an embodiment of the present disclosure; fig. 9 is a schematic structural diagram illustrating another method for forming a backside of a substrate in a method for fabricating a solar cell according to an embodiment of the present disclosure; fig. 10 is another schematic structural diagram of an initial textured structure formed in a solar cell manufacturing method according to an embodiment of the present disclosure; fig. 11 is a schematic view of another structure for forming the backside of the substrate in the method for manufacturing a solar cell according to an embodiment of the present disclosure; fig. 12 is a schematic view of another structure for forming the backside of the substrate in the method for manufacturing a solar cell according to an embodiment of the present disclosure; fig. 13 is a schematic structural diagram illustrating a first bump structure formed in a solar cell manufacturing method according to an embodiment of the present disclosure; fig. 14 is a schematic structural diagram illustrating formation of a tunneling dielectric layer in a solar cell manufacturing method according to an embodiment of the present disclosure; fig. 15 is a schematic structural diagram illustrating a doped conductive layer formed in a solar cell manufacturing method according to an embodiment of the present disclosure; fig. 16 is a schematic structural diagram illustrating a passivation layer formed in a solar cell manufacturing method according to an embodiment of the present disclosure; fig. 17 is a schematic structural diagram of a back electrode formed in a solar cell manufacturing method according to an embodiment of the present disclosure.
Referring to fig. 6, a substrate 100 is provided, the substrate 100 having opposite front 101 and back 102 sides, the front 101 and back 102 sides of the substrate having a textured structure.
In some embodiments, a solution texturing method can be adopted to prepare a textured structure, and the textured structure can increase the refraction times of light on the surface of the solar cell, thereby being beneficial to the solar cellThe sheet absorbs light so as to achieve the maximum utilization rate of the solar energy value of the cell sheet. Specifically, the substrate 100 is monocrystalline silicon, and a mixed solution of an alkali solution and an alcohol solution can be adopted to perform a texturing process on the surface of the substrate 100; the substrate 100 is polysilicon, and the surface of the substrate 100 may be subjected to a texturing process using an acid solution. In other embodiments, the textured structure may be prepared using a laser texturing process, Reactive Ion Etching (RIE) texturing process. The laser texturing process utilizes high-energy laser pulses to irradiate the surface of a silicon wafer to rapidly heat, melt and gasify local materials of the substrate 100, and a concave-convex textured structure is formed in a light irradiation area. The process flow of the reverse ion etching texturing process is to place the cleaned substrate 100 in a solution containing SF 6 、O 2 In the oxidizing mixed gas, gas glow discharge under a high-frequency Radio Frequency (RF) electric field ionizes and decomposes the gas into plasma containing free radicals, ions and free electrons, and the physical effect of the plasma on an electric field to accelerate impact on a silicon wafer and the chemical etching effect of free active chemical radicals are synthesized, so that a nano-scale micro pyramid array, namely a textured structure, is formed on the surface of the substrate 100.
In some embodiments, the substrate 100 has a doping element therein, and the doping element type is N-type or P-type. Specifically, the doping element may be implanted into the substrate 100 through an ion implantation process or a laser doping process.
Referring to fig. 7, the back surface 102 includes a first region 103 and a second region 104 adjacent to the first region 103, and a secondary texturing process is performed on the back surface 102 of the substrate 100 of the first region 103 to form an initial textured structure.
In some embodiments, the secondary texturing process is a laser process; the parameters of the laser process include: the laser wavelength comprises 355 nm-460 nm, the laser pulse width comprises 20 ps-80 ps, the laser power comprises 30W-100W, the size of a laser spot comprises 15 mu m-50 mu m, the laser frequency is 200 kHz-2 MHz, and the laser linear speed comprises 20 m/s-40 m/s. Preferably, the parameters of the laser process include: the laser wavelength comprises 355 nm-400 nm, the laser pulse width comprises 20 ps-50 ps, the laser power comprises 50W-80W, the size of a laser spot can be set according to 10% -30% of the size of a required laser area, the laser frequency is 300 kHz-800 kHz, and the laser linear speed comprises 20 m/s-30 m/s.
In some embodiments, the laser process is an isotropic texturing method, and the principle is that a high-energy laser pulse is used for irradiating the surface of a silicon wafer to enable local materials to be rapidly heated, melted and gasified, and a concave-convex surface microstructure is formed in a light irradiation area, so that the size of an initial textured structure formed in the first area 103 after etching is smaller than that of a textured structure of the second area 104. Specifically, the width of the bottom surface of the initial textured structure formed in the first region 103 after etching is smaller than the width of the bottom surface of the textured structure of the second region 104, and the height difference from the top of the initial textured structure to the back of the substrate is smaller than the height difference from the top of the initial textured structure of the second region 104 to the back of the substrate.
Referring to fig. 8, the extending direction of the first region 103 is the same as the extending direction of the subsequently formed back electrode, and the extending length of the first region 103 corresponds to the extending length of the back electrode. In other embodiments, referring to fig. 9, the back surface includes a plurality of first regions arranged along the second direction Y; the distance range between the adjacent first areas is 10 mm-20 mm, and the distance between the adjacent first areas 103 can be 10.3mm, 13mm, 15.1mm, 17mm or 19 mm.
Referring to fig. 10, the first region 103 includes a first portion 107 and a second portion 108, the first portion 107 is located in a region for forming the third protrusion structure, and the second portion 108 is located in a region for forming the first protrusion structure. The laser parameters of the first section 107 are different from the laser parameters of the second section 108, the width of the bottom surface of the first initial textured structure formed on the first section 107 is greater than the width of the bottom surface of the second initial textured structure of the second section 108, and the height difference from the top of the first initial textured structure to the back of the substrate is greater than the height difference from the top of the second initial textured structure of the second section 108 to the back of the substrate.
The arrangement of the first portion 107 and the second portion 108 in fig. 11 is the same as the arrangement of the first region 103 in fig. 8, and the arrangement of the first portion 107 and the second portion 108 in fig. 12 is the same as the arrangement of the first region 103 in fig. 9, which is not described in detail herein.
It is understood that the first portion 107 shown in fig. 12 is arranged in the same manner as the second portion 108, that is, the first portion 107 and the second portion 108 are arranged at intervals along the first direction X; the arrangement of the first portion 107 may also be different from that of the second portion 108, for example, the first portion 107 and the second portion 108 are arranged in a staggered manner along the first direction X.
Referring to fig. 2 to 4 and 13, an emitter 110 is formed on the front surface 101 of the substrate 100, and a polishing process is performed on the back surface of the substrate 100 to form a first bump structure 111 and a second bump structure 112.
In some embodiments, the polishing treatment may be performed by using an alkaline solution or an acidic solution, so that the back surface 102 of the substrate 100 is a polished surface, which may increase internal reflection of light, reduce a recombination rate of a carrier surface, and improve photoelectric conversion efficiency of the cell. Specifically, the etching portion of the initial textured structure of the first region 103 by the alkaline solution or the acidic solution forms a first protruding structure 111 having a top surface, and the etching portion of the textured structure of the second region 104 by the alkaline solution or the acidic solution forms a second protruding structure 112 having a top surface. It can be understood that, in the same time and under the same reaction environment (reaction solution, reaction temperature and reaction pressure), the etching degree of the initial texture structure and the texture structure positioned in the second area is the same, since the width of the bottom side of the initial pile of the first zone 103 is smaller than the width of the bottom side of the pile of the second zone 104, and the height difference from the top of the initial textured structure to the back of the substrate is less than the height difference from the top of the initial textured structure of the second region 104 to the back of the substrate, the bottom width of the etched first raised structures 111 is less than the bottom width of the second raised structures 112 of the second region 104, the top width of the first raised structures 111 is less than the top width of the second raised structures 112 of the second region 104, and the height difference from the top surface of the first raised structure 111 to the back surface of the substrate is smaller than the height difference from the top surface of the second raised structure 112 of the second region 104 to the back surface of the substrate.
In some embodiments, since the initial textured structure is formed by the laser process, surface/subsurface damage such as cracks, lamination, phase change and the like may be introduced to the surface of the initial textured structure, resulting in an increase in the composite current of the initial textured structure, and the surface/subsurface damage layer may be removed by etching with the solution subjected to the polishing treatment. The antireflective effect of the etched first bump structure 111 is weakened, which is beneficial to improving the efficiency of the battery.
In some embodiments, the first raised structure 111 includes a plateau raised structure, a plateau-like raised structure, or other raised structure having a sloped surface and a top surface, and the top surface of the plateau raised structure is a polygonal plane. The second raised structure 112 includes a plateau raised structure, a plateau-like raised structure, or other raised structure having a sloped surface and a top surface.
The first region 103 further includes third protruding structures 113, and the third protruding structures 113 are spaced apart from the first protruding structures 111 along the first direction X. The first initial suede structure is polished to form a third protrusion structure 113, and the second initial suede structure is polished to form a first protrusion structure 111. The width of the third bump structure 113 may be equal to the width of the second bump structure 112, and specifically, the width of the top surface of the third bump structure 113 may be equal to the width of the top surface of the second bump structure 112, and the width of the bottom surface of the third bump structure 113 may be equal to the width of the bottom surface of the second bump structure 112. In other embodiments, the width of the third protruding structure 113 is between the width of the first protruding structure 111 and the width of the second protruding structure 112.
In some embodiments, under the same back electrode 131, the total width of the cross section of the first protruding structure 111 contacting the back surface 102 is greater than or equal to the total width of the cross section of the third protruding structure 113 contacting the back surface 102. Specifically, the ratio of the total width of the cross section of the first protruding structure 111 contacting the back surface to the total width of the cross section of the third protruding structure 113 contacting the back surface is 4: 1-1: 1, and further, the ratio of the total width of the cross section of the first protruding structure 111 contacting the back surface to the total width of the cross section of the third protruding structure 113 contacting the back surface is 3: 1-1: 1, which may be 1:1, 1.5:1, 2:1, or 2.8: 1. The third protrusion structures 113 occupy too much, which may affect the back reflection of the solar cell to the long-wavelength light, and further affect the cell efficiency.
In some embodiments, the height difference H between the top surface of the first bump structure 111 and the back surface 102 of the substrate 100 1 Less than or equal to the third bump knotThe height difference H between the top surface of the structure 113 and the back surface 102 of the substrate 100 3 . The third bump structure 113 includes a plateau bump structure, a plateau-like bump structure, or other bump structure having a slope and a top surface.
Referring to fig. 14, a tunnel dielectric layer 121 is formed on the surfaces of the first region 103 and the second region 104 on the back surface of the substrate 100.
In some embodiments, the material of tunnel dielectric layer 121 may include, but is not limited to, aluminum oxide, silicon nitride, silicon oxynitride, intrinsic amorphous silicon, intrinsic polysilicon, and other dielectric materials having a tunneling effect.
Referring to fig. 15, a doped conductive layer 122 is formed on the surface of tunnel dielectric layer 121 far from substrate 100.
In some embodiments, the material of the doped conductive layer 122 may be at least one of a polycrystalline semiconductor, an amorphous semiconductor, or a microcrystalline semiconductor, and preferably, the material of the doped conductive layer 122 includes at least one of polycrystalline silicon, amorphous silicon, or microcrystalline silicon. The process steps for forming the doped conductive layer 122 may be: firstly, a conductive film and a borosilicate glass BSG layer are formed on the surface of the tunnel dielectric layer 121, then a laser process is adopted to perform doping treatment to form a doped conductive layer 122, and finally the residual BSG layer is removed. In other embodiments, the doping process is performed using an ion implantation process. The material of the conductive film is at least one of amorphous silicon or microcrystalline silicon.
Referring to fig. 16, a passivation layer 123 and a first passivation layer 124 are formed, where the passivation layer 123 is located on the surface of the doped conductive layer 122, and the passivation layer 123 may be regarded as a post-passivation layer; the first passivation layer 124 is located on the surface of the emitter 110 away from the substrate 100, and the first passivation layer 124 is regarded as a front passivation layer.
Referring to fig. 17, a back electrode 131 is formed, the back electrode 131 is arranged along the first direction X, the back electrode 131 corresponds to the substrate 100 of the first region 103, and the back electrode 131 is in contact with the doped conductive layer 122. In some embodiments, the width of the substrate 100 of the first region 103 is greater than or equal to the width of the back electrode 131 along the first direction X.
With continued reference to fig. 17, an electrode 132 is formed, the electrode 132 extending through the first passivation layer 124 and contacting the emitter 110.
It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples for carrying out the present application, and that various changes in form and details may be made therein without departing from the spirit and scope of the present application in practice. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the application, and it is intended that the scope of the application be limited only by the claims appended hereto.

Claims (14)

1. A solar cell, comprising:
the substrate is provided with a front surface and a back surface which are opposite, the back surface comprises a first area and a second area adjacent to the first area, and the substrate of the first area is internally provided with doping elements which are N-type or P-type; along a first direction, the width of a first protruding structure of the first area is smaller than that of a second protruding structure of the second area, the first protruding structure comprises a platform protruding structure, and the top surface of the platform protruding structure is a polygonal plane;
the tunneling dielectric layer is positioned on the back surface of the substrate;
the doped conducting layer is positioned on the surface, far away from the back surface of the substrate, of the tunneling dielectric layer, the doped conducting layer is provided with doping elements, and the types of the doping elements in the doped conducting layer are the same as those in the first region;
the back electrodes are arranged along a first direction, correspond to the substrate of the first area, and are in contact with the doped conducting layer.
2. The solar cell of claim 1, wherein a substrate width of the first region is equal to or greater than a width of the back electrode along the first direction; the substrate of the first region comprises at least one first protruding structure.
3. The solar cell of claim 2, wherein the number of the first protrusion structures is two; along the first direction, the distance between the adjacent first protruding structures ranges from 0.1 mu m to 10 mu m.
4. The solar cell of any of claims 1-3, wherein the width of the bottom surface of the first raised structure is less than the width of the bottom surface of the second raised structure.
5. The solar cell of any of claims 1-3, wherein a width of a top surface of the first raised structure is less than a width of a top surface of the second raised structure.
6. The solar cell of claim 5, wherein the width of the top surface of the first protrusion structure is 1 μm to 2 μm.
7. The solar cell of claim 1, wherein a height difference between the top surface of the first raised structure and the back surface of the substrate is less than or equal to a height difference between the top surface of the second raised structure and the back surface of the substrate.
8. The solar cell of claim 7, wherein a height difference between the top surface of the first protrusion structure and the back surface of the substrate is 200nm to 500 nm.
9. The solar cell of claim 1, wherein the first region further comprises third raised structures spaced apart from the first raised structures along the first direction.
10. The solar cell of claim 9, wherein the total width of the cross section of the first raised structure in contact with the back surface is greater than or equal to the total width of the cross section of the third raised structure in contact with the back surface under the same back electrode.
11. The solar cell of claim 10, wherein a ratio of a total width of a cross section of the first protrusion structure contacting the back surface to a total width of a cross section of the third protrusion structure contacting the back surface is in a range of 1:1 to 4: 1.
12. The solar cell of claim 9, wherein the width of the first raised structure is less than the width of the third raised structure.
13. The solar cell of claim 9, wherein a height difference between the top surface of the first raised structure and the back surface of the substrate is less than or equal to a height difference between the top surface of the third raised structure and the back surface of the substrate.
14. A photovoltaic module, comprising:
a battery string formed by connecting a plurality of solar cells according to any one of claims 1 to 13;
the packaging adhesive film is used for covering the surface of the battery string;
and the cover plate is used for covering the surface of the packaging adhesive film, which deviates from the battery string.
CN202210738558.4A 2022-06-28 2022-06-28 Solar cell and photovoltaic module Pending CN114823951A (en)

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CN116404071A (en) * 2023-06-07 2023-07-07 晶科能源(海宁)有限公司 Solar cell, preparation method thereof and photovoltaic module
US11791426B1 (en) 2022-09-08 2023-10-17 Zhejiang Jinko Solar Co., Ltd. Photovoltaic cell and photovoltaic module
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