CN112838133A - Solar cell and preparation method thereof - Google Patents

Solar cell and preparation method thereof Download PDF

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CN112838133A
CN112838133A CN202011621865.1A CN202011621865A CN112838133A CN 112838133 A CN112838133 A CN 112838133A CN 202011621865 A CN202011621865 A CN 202011621865A CN 112838133 A CN112838133 A CN 112838133A
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electrode
secondary doping
diffusion layer
layer
solar cell
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朱俊
朱凡
陆红艳
张松
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Dier Laser Technology Wuxi 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
    • H01L31/02—Details
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    • 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
    • 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
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    • 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
    • H01L31/02168—Coatings for devices characterised by at least one potential jump barrier or surface barrier for solar cells the coatings being antireflective or having enhancing optical properties for the 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
    • H01L31/18—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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    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/547—Monocrystalline silicon PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract

The invention provides a solar cell and a preparation method thereof, wherein the solar cell comprises a substrate, wherein the front surface of the substrate is provided with a diffusion layer and a front surface electrode, and the front surface electrode forms ohmic contact with the diffusion layer through an antireflection layer; the diffusion layer is provided with a secondary doping area, the shape of the secondary doping area is at least one line-shaped line, the line is crossed with the orthographic projection of at least one front electrode on the surface of the diffusion layer but not overlapped, and the ohmic contact of the secondary doping area and the front electrode is only at the crossed position. According to the invention, the secondary doping region with low sheet resistance is arranged on the diffusion layer, and is in ohmic contact with the front electrode only at the intersection, so that the collecting effect of carriers can be improved, and the conversion efficiency of the battery is improved.

Description

Solar cell and preparation method thereof
Technical Field
The invention relates to the technical field of solar cells, in particular to a solar cell and a preparation method thereof.
Background
Due to the excessive use of fossil energy, the shortage of traditional energy sources such as coal and petroleum is caused, the global climate is warmed, the environmental pollution is increasingly serious, and people need to find a renewable green energy source. Of all sustainable energy sources, solar energy is undoubtedly the cleanest, most common and most potential alternative.
At present, the technology of the crystalline silicon solar cell industry is mature, however, compared with the conventional energy, the development of the crystalline silicon solar cell is restricted by the relatively higher cost and the lower efficiency, and how to reduce the cost and improve the conversion efficiency is always the main research direction of the technicians in the field.
It has been found in research that the gate line electrode is one of the key factors affecting efficiency. The grid line electrodes on the surface of the solar cell are designed to collect photocurrent to the maximum extent, which means that the grid line electrodes are thicker and thicker, and the light receiving area of the cell is necessarily reduced. The design of the grid line electrode should be a match between the light receiving area and the collected current. Although the grid line is designed to be very high and very narrow at present, the use amount of the paste is increased, higher requirements on the paste, the screen printing plate and printing are met, and the preparation cost is increased.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: provided are a solar cell and a method for manufacturing the same, which can improve the collection effect of carriers, thereby improving the conversion efficiency of the cell.
The technical scheme adopted by the invention for solving the technical problems is as follows: a solar cell comprises a substrate, wherein a diffusion layer and a front electrode are arranged on the front surface of the substrate, and the front electrode forms ohmic contact with the diffusion layer through an antireflection layer; (ii) a
The diffusion layer is provided with a secondary doping area, the shape of the secondary doping area is at least one line-shaped line, the line is crossed with the orthographic projection of at least one front electrode on the surface of the diffusion layer but not overlapped, and the ohmic contact of the secondary doping area and the front electrode is only at the crossed position.
According to the scheme, the lines are one or any combination of straight lines, broken lines or curves.
According to the scheme, the line type of each line is the same, and the distance between every two adjacent lines is equal.
According to the scheme, the front electrode comprises a first electrode and a second electrode; the first electrodes are arranged on the first substrate, and each first electrode is crossed with at least one second electrode but not overlapped with the second electrode;
the lines intersect with but do not coincide with the orthographic projection of the at least one second electrode on the surface of the diffusion layer.
According to the scheme, the first electrode is a plurality of thick grid line electrodes which are parallel to each other, the second electrode is a plurality of thin grid line electrodes which are parallel to each other, and the second electrode is perpendicular to the first electrode.
According to the scheme, the solar cell is a BSF cell, a MWT cell, a PERC cell, a PERL cell, a PERT cell or a Topcon cell.
The preparation method of the solar cell comprises a diffusion step and an electrode preparation step, and further comprises a front secondary doping step: and carrying out secondary doping on the diffusion layer with the front surface formed in the diffusion step to form a secondary doping area.
According to the method, the secondary doping adopts a laser irradiation process, and the laser scans according to a laser irradiation path to form a secondary doping area.
According to the method, the spot size of the laser focused on the surface of the diffusion layer is 30-500 mu m.
According to the method, the method specifically comprises the following steps:
s1, texturing the surface of the substrate;
s2, a diffusion step, wherein a diffusion layer and an oxidation layer are formed on the front surface of the substrate;
s3, front secondary doping: performing secondary doping on the diffusion layer with the front surface formed in the diffusion step to form a secondary doping area and reduce the sheet resistance of the secondary doping area;
s4, removing the oxide layer and the back junction and the side junction of the diffusion layer to insulate the front surface and the back surface;
s5, preparing a front antireflection layer;
s6, preparing a front electrode and a back electrode;
and S7, sintering to enable the front electrode to penetrate through the anti-reflection layer to form ohmic contact with the diffusion layer and the intersection of the secondary doping region, and enabling the back electrode to form ohmic contact with the substrate.
The invention has the beneficial effects that:
1. according to the solar cell and the preparation method thereof, secondary doping is carried out on the surface of a diffused semi-finished product of the solar cell, the sheet resistance of a secondary doping area is reduced, the secondary doping area is not in ohmic contact with a front electrode, but only in ohmic contact at a cross position, so that current carriers can be collected through the secondary doping area, and the collection effect of the current carriers can be improved through the secondary doping area with low sheet resistance; thus, even if the number of front electrodes is reduced, sufficient carriers can be collected.
2. When the front electrode is prepared, the number of grid lines on the surface of the cell is reduced, the shading area of the front electrode can be effectively reduced, and the light receiving area is increased, so that more photons irradiate the surface of the solar cell to form more carriers; the reduction of grid lines can also reduce the consumption of grid line materials and reduce the material cost.
Drawings
Fig. 1 is a schematic diagram of a second doping according to an embodiment of the invention.
Fig. 2 is a schematic diagram of second doping according to an embodiment of the invention.
Fig. 3 is a schematic diagram of third and second doping according to an embodiment of the invention.
Fig. 4 is a flowchart of a method according to a first embodiment of the invention.
In the figure: the manufacturing method comprises the following steps of 1-1-a coarse grid line electrode, 1-2-a fine grid line electrode, 2-a diffusion layer, 3-a secondary doping region, 3-1-a first secondary doping region, 3-2-a second secondary doping region, 3-3-a third secondary doping region and 3-4-a fourth secondary doping region.
Detailed Description
The invention is further illustrated by the following specific examples and figures.
The invention provides a solar cell, which comprises a substrate, wherein the front surface of the substrate is provided with a diffusion layer and a front surface electrode, and the front surface electrode forms ohmic contact with the diffusion layer through an antireflection layer; the diffusion layer is provided with a secondary doping area in ohmic contact with the front electrode, the shape of the secondary doping area is at least one line-shaped line, the line is crossed with the orthographic projection of the front electrode on the surface of the diffusion layer but not overlapped, and the ohmic contact of the secondary doping area and the front electrode is only at the crossed position. The diffusion layer is provided with the secondary doping area with low sheet resistance, and the orthographic projection of the secondary doping area and the orthographic projection of the surface of the diffusion layer of the front electrode are crossed but do not coincide, so that the secondary doping area can play a good carrier collection role, and even if the front electrode is reduced, enough carriers can be still collected; on the basis, the number of the front electrodes is reduced, and the shading area of the front electrodes can be effectively reduced, so that more photons irradiate the surface of the solar cell, and the conversion efficiency is improved. Meanwhile, the use of materials can be reduced by reducing the number of the front electrodes, and the cost of raw materials is reduced.
The lines are any line type, can be continuous solid lines or discontinuous dotted lines, and can be straight lines, broken lines, curves and the like, and the combination of straight lines and curves and the like. The specific configuration may be set according to the kind of battery and the requirements and convenience of the construction process.
The scheme of the invention can be suitable for BSF batteries, MWT batteries, PERC batteries, PERL batteries, PERT batteries or Topcon batteries. Several examples are provided below for further illustration.
The first embodiment is as follows:
the embodiment provides a preparation method of a solar cell, which is applicable to a conventional BSF cell, and as shown in fig. 4, a front secondary doping step is added after surface texturing and diffusion, then other processes are performed, and finally an electrode grid line is screen-printed and sintered. Specifically, the method comprises the following steps:
(1) selecting a monocrystalline silicon wafer to carry out surface texturing, namely, carrying out texturing treatment on the monocrystalline silicon wafer to form a pyramid textured surface, and then cleaning and drying.
In this embodiment, a silicon substrate is provided first. In terms of material, the silicon substrate can be monocrystalline silicon, polycrystalline silicon or quasi-monocrystalline silicon; in terms of doping type, the silicon substrate is P-type silicon.
(2) And carrying out phosphorus diffusion on the front surface of the silicon substrate to prepare a PN junction so as to form a diffusion layer and an oxidation layer, wherein the oxidation layer is a phosphorosilicate glass layer.
The sheet resistance range is 80-150 omega/□ when the diffusion is determined by the step (1), and the surface concentration is 1 multiplied by 1018cm-3-1×1022cm-3The thickness of the phosphosilicate glass layer formed during diffusion is 1-100 nm.
(3) Irradiating the surface of the diffusion layer with laser to perform secondary doping, wherein the front electrode comprises a first electrode and a second electrode; the second electrodes and the first electrodes are multiple, and each second electrode is crossed with at least one first electrode but not overlapped. Specifically, as shown in fig. 1, the first electrode is a plurality of thick grid electrode lines 1-1 parallel to each other, the second electrode is a plurality of thin grid electrode lines 1-2 parallel to each other, and the second electrode is perpendicular to the first electrode. The secondary doping area 3 is crossed but not coincident with the orthographic projection of the fine grid electrode 1-2 prepared later on the surface of the diffusion layer 2. Specifically, the laser is scanned along the laser irradiation path to obtain the secondary doping region 3 shown in fig. 1, thereby completing the secondary doping.
After secondary doping, the sheet resistance range of the laser irradiation area is 50-100 omega/□, and the surface concentration is 5 multiplied by 1017cm-3-1×1022cm-3(ii) a In this embodiment, the laser power is 40W, the wavelength is 532nm (green), the spot is square, and the size is 30-500 μm. Other lasers can be adopted for doping, and the effect can be achieved.
(4) And removing the phosphorosilicate glass layer by wet etching, and simultaneously removing the back junction and the side junction of the diffusion layer to insulate the front surface and the back surface.
(5) And depositing a silicon nitride film on the front surface as an antireflection layer.
(6) And screen printing back silver and back aluminum on the back surface.
(7) And screen printing is carried out on the front surface of the silicon substrate, so that the number of second electrodes is reduced. The first electrode, i.e. the coarse gate electrode 1-1, is parallel to the secondary doping region 3 formed in step (3), and the second electrode, i.e. the fine gate electrode 1-2, is perpendicular to the secondary doping region 3 formed in step (3), as shown in fig. 1. In the embodiment, the number of the first electrodes is 5, the number of the second electrodes is 50-100, and the width of the second electrodes is 20-50 μm.
(8) And sintering to enable the front electrode to penetrate through the anti-reflection layer, the diffusion layer and the intersection of the secondary doping region to form ohmic contact, and the back electrode to form ohmic contact with the silicon substrate.
In this embodiment, for process convenience, the coarse grid line electrode 1-1 and the fine grid line electrode 1-2 are both set to be linear lines, and the distances between adjacent grid line electrodes are equal. For the convenience of laser scanning, the secondary doping regions 3 are mutually parallel straight lines, and the intervals between adjacent lines are equal.
Comparative example one: this is a normal BSF battery
(1) Selecting a monocrystalline silicon wafer to carry out surface texturing, namely, carrying out texturing treatment on the monocrystalline silicon wafer to form a pyramid textured surface, and then cleaning and drying.
In this comparative example, a silicon substrate was first provided. In terms of material, the silicon substrate can be monocrystalline silicon, polycrystalline silicon or quasi-monocrystalline silicon; in terms of doping type, the silicon substrate is P-type silicon.
(2) And carrying out phosphorus diffusion on the front surface of the silicon substrate to prepare a PN junction so as to form a diffusion layer and an oxidation layer, wherein the oxidation layer is a phosphorosilicate glass layer. The sheet resistance range during diffusion is 80-150 omega/□.
(3) And removing the phosphorosilicate glass layer by wet etching, and simultaneously removing the back junction and the side junction of the diffusion layer to insulate the front surface and the back surface.
(4) And depositing a silicon nitride film on the front surface as an antireflection layer.
(5) And screen printing back silver and back aluminum on the back surface.
(6) And screen printing is carried out on the front surface of the silicon substrate. In this comparative example, the number of the first electrodes was 5, the number of the second electrodes was 120, and the width of the second electrodes was 35 to 40 μm.
(7) Sintering makes the front electrode penetrate through the antireflection layer and the diffusion layer to form ohmic contact with the diffusion layer, and the back electrode forms ohmic contact with the silicon substrate.
Example two:
the present embodiment provides a method for manufacturing a solar cell, which has the same principle and concept as the first embodiment, and is different from the first embodiment in that: suitable for use in a PERC cell, comprising the steps of:
(1) selecting a monocrystalline P-type silicon wafer to carry out surface texturing, namely, carrying out texturing treatment on the monocrystalline P-type silicon wafer to form a pyramid textured surface, and then cleaning and drying.
(2) Carrying out phosphorus diffusion on the front surface of the crystalline silicon to prepare a PN junction so as to form a diffusion layer and a phosphorus-silicon glass layer; the sheet resistance range is 80-150 omega/□ when the diffusion is determined by the step (1), and the surface concentration is 1 multiplied by 1018cm-3-1×1022cm-3The thickness of the phosphosilicate glass layer formed during diffusion is 1-100 nm.
(3) The front surface is irradiated with laser light for secondary doping, and the secondary doped region is shown in fig. 2. Laser scanning is performed on the diffusion layer 2 to form a secondary doping region, and in the embodiment, the secondary doping region comprises a first secondary doping region 3-1 and a second secondary doping region 3-2. The line type of the first secondary doping region 3-1 is a straight line parallel to the coarse grid electrode 1-1, and the distances between the adjacent first secondary doping regions 3-1 are equal; the line type of the second secondary doping region 3-2 is a straight line parallel to the fine grid electrode 1-2, and the second secondary doping region 3-2 is perpendicular to the first secondary doping region 3-1. When laser scanning is performed, the laser irradiation path is not limited, and only the secondary doping region needs to be formed. One laser shot formation is preferred to save process and reduce laser cost.
After secondary doping, the sheet resistance range of the laser irradiation area is 50-100 omega/□, and the surface concentration is 1 multiplied by 1017cm-3-5×1022cm-3(ii) a The laser power is 40W, the wavelength is 532nm (green light), and the spot size is 30-500 μm.
(4) And removing the phosphorosilicate glass layer by wet etching, and simultaneously removing the back junction and the side junction of the diffusion layer to insulate the front surface and the back surface.
(5) An aluminum oxide film is deposited on the back surface as a passivation layer, followed by a silicon nitride film deposited on the back surface as a protective layer.
(6) Depositing a silicon nitride film on the front surface as an antireflection layer;
(7) forming a contact window of the back surface metal layer and the crystalline silicon substrate on the back surface by adopting laser, and carrying out screen printing on the back surface to carry out back silver and back aluminum;
(8) the front surface is screen printed. 5 thick grid line electrodes 1-1, 50-100 thin grid line electrodes 1-2 and 20-50 μm in width;
(9) and sintering to enable the front electrode to penetrate through the antireflection layer to form ohmic contact with the diffusion layer and the intersection of the secondary doping region, and the back electrode to form ohmic contact with the substrate.
Comparative example two:
a PERC cell comprising the steps of:
(1) selecting a monocrystalline P-type silicon wafer to carry out surface texturing, namely, carrying out texturing treatment on the monocrystalline P-type silicon wafer to form a pyramid textured surface, and then cleaning and drying.
(2) Carrying out phosphorus diffusion on the front surface of the crystalline silicon to prepare a PN junction so as to form a diffusion layer and a phosphorus-silicon glass layer; the sheet resistance range during diffusion is determined to be 80-150 omega/□ by the step (1).
(3) Performing secondary doping on the front surface of the diffused crystalline silicon by using laser, wherein the power of the laser is 45W, the wavelength is 532nm (green light), the size of a light spot is 120 mu m, and a laser irradiation pattern is consistent with that of a front screen printing fine grid line electrode; after secondary doping, the square resistance range of the laser irradiation area is 60-90 omega/□.
(4) And removing the phosphorosilicate glass layer by wet etching, and simultaneously removing the back junction and the side junction of the diffusion layer to insulate the front surface and the back surface.
(5) An aluminum oxide film is deposited on the back surface as a passivation layer, followed by a silicon nitride film deposited on the back surface as a protective layer.
(6) Depositing a silicon nitride film on the front surface as an antireflection layer;
(7) forming a contact window of the back surface metal layer and the crystalline silicon substrate on the back surface by adopting laser, and carrying out screen printing on the back surface to carry out back silver and back aluminum;
(8) the front surface is screen printed. In this comparative example, the number of the first electrodes was 5, the number of the second electrodes was 128, and the width of the second electrodes was 35 to 40 μm.
(9) And sintering to enable the front electrode to penetrate through the antireflection layer to form ohmic contact with the diffusion layer and the intersection of the secondary doping region, and the back electrode to form ohmic contact with the substrate.
Example three:
the present embodiment provides a method for manufacturing a solar cell, which has the same principle and concept as the first embodiment, and is different from the first embodiment in that: suitable for a Topcon cell, comprising the steps of:
(1) selecting a monocrystalline N-type silicon wafer to carry out surface texturing, namely, carrying out texturing treatment on the monocrystalline N-type silicon wafer to form a pyramid textured surface, and then cleaning and drying.
(2) And carrying out boron diffusion on the front surface of the crystalline silicon to prepare a PN junction so as to form a diffusion layer and a borosilicate glass layer. (ii) a The sheet resistance range is 50-200 omega/□ when the diffusion is determined by the step (1), and the surface concentration is 1 multiplied by 1018cm-3-1×1022cm-3The thickness of the borosilicate glass layer formed during diffusion is 1-100 nm.
(3) The front surface is irradiated with laser light for secondary doping, and the secondary doped region is shown in fig. 3. And performing laser scanning on the diffusion layer 2 to obtain a secondary doping region, wherein the secondary doping region comprises a third secondary doping region 3-3 and a fourth secondary doping region 3-4 in the embodiment. The line type of the third secondary doping regions 3-3 is a straight line parallel to each other, and the distances between the adjacent third secondary doping regions 3-3 are equal; the line shapes of the fourth secondary doping regions 3-4 are parallel straight lines. The third secondary doping region 3-3 and the fourth secondary doping region 3-4 are perpendicular to each other, the included angles between the third secondary doping region 3-3 and the coarse grid line electrode 1-1 and the fine grid line electrode 1-2 are both 45 degrees, and the included angles between the fourth secondary doping region 3-4 and the coarse grid line electrode 1-1 and the fine grid line electrode 1-2 are both 45 degrees. The laser irradiation path and the doping times are not limited, as long as the finally formed secondary doping regions are the third secondary doping region 3-3 and the fourth secondary doping region 2-4.
After secondary doping, the sheet resistance range of the laser irradiation area is 50-100 omega/□, and the surface concentration is 1 multiplied by 1017cm-3-1×1022cm-3(ii) a The laser power is 50W, the wavelength is 532nm (green light), and the spot size is 30-500 μm.
(4) And removing the borosilicate glass layer by wet etching, and simultaneously removing the back junction and the side junction of the diffusion layer to insulate the front surface and the back surface.
(5) Depositing a silicon oxide film on the back surface as a tunneling oxide layer; and depositing an amorphous silicon layer and annealing.
(6) And depositing an aluminum oxide film and a silicon nitride film on the front surface respectively as a passivation layer and an antireflection layer.
(7) And depositing a silicon nitride film on the back surface as a protective layer.
(8) The back surface was screen printed with silver electrodes.
(9) The front surface is screen printed with silver electrodes, and the coarse grid electrode 1-1 and the fine grid electrode 1-2 are shown in fig. 3. The number of the coarse grid line electrodes 1-1 is 5, the number of the fine grid line electrodes 1-2 is 50-100, and the width of the fine grid line electrodes 1-2 is 20-60 mu m.
(10) And sintering to enable the front electrode to penetrate through the antireflection layer to form ohmic contact with the diffusion layer and the intersection of the secondary doping region, and the back electrode to form ohmic contact with the substrate.
Comparative example three: this is a normal Topcon cell
(1) Selecting a monocrystalline N-type silicon wafer to carry out surface texturing, namely, carrying out texturing treatment on the monocrystalline N-type silicon wafer to form a pyramid textured surface, and then cleaning and drying.
(2) And carrying out boron diffusion on the front surface of the crystalline silicon to prepare a PN junction so as to form a diffusion layer and a borosilicate glass layer. (ii) a The sheet resistance range during diffusion is determined to be 50-200 omega/□ by the step (1).
(3) And removing the borosilicate glass layer by wet etching, and simultaneously removing the back junction and the side junction of the diffusion layer to insulate the front surface and the back surface.
(4) Depositing a silicon oxide film on the back surface as a tunneling oxide layer; and depositing an amorphous silicon layer and annealing.
(5) And depositing an aluminum oxide film and a silicon nitride film on the front surface respectively as a passivation layer and an antireflection layer.
(6) And depositing a silicon nitride film on the back surface as a protective layer.
(7) The back surface was screen printed with silver electrodes.
(8) And screen printing the silver electrode, the coarse grid line electrode and the fine grid line electrode on the front surface. The number of the coarse grid line electrodes is 5, the number of the fine grid line electrodes is 120, and the width of the fine grid line electrodes is 35-40 mu m.
(9) And sintering to enable the front electrode to be in ohmic contact with the diffusion layer through the antireflection layer, and the back electrode to be in ohmic contact with the substrate.
A table comparing the cell efficiency and the positive silver unit consumption between the above three examples and the comparative example is given below.
Efficiency of battery Silver consumption (mg)
Comparative example 1 20.50％ 95
Example 1 20.52％ 82
Comparative example 2 22.60％ 99
Example 2 22.63％ 90
Comparative example 3 23.80％ 90
Example 3 23.85％ 81
By combining the embodiment and the comparative example, the method provided by the invention can reduce the number of the front-side fine grid electrodes by 5-25% by adopting the laser secondary doping as a carrier collecting mode, so that the shading area of the fine grid lines can be correspondingly reduced, the photons received by the surface of the solar cell can be correspondingly increased, and the conversion efficiency of the cell can be improved; in addition, the number of the front fine grid electrodes is reduced, so that the consumption of slurry of each cell is reduced correspondingly, and the cost of the solar cell can be reduced.
The secondary doping region patterns in fig. 1-3 are not only suitable for the cell corresponding to the embodiments, but also for other cells; meanwhile, the pattern of the secondary doping region is not limited to the 3 kinds listed in the present embodiment. Also, fig. 2 is only visually seen in a larger number than fig. 1.
The above embodiments are only used for illustrating the design idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention accordingly, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes and modifications made in accordance with the principles and concepts disclosed herein are intended to be included within the scope of the present invention.

Claims (10)

1. A solar cell comprises a substrate, wherein a diffusion layer and a front electrode are arranged on the front surface of the substrate, and the front electrode forms ohmic contact with the diffusion layer through an antireflection layer; the method is characterized in that:
the diffusion layer is provided with a secondary doping area, the shape of the secondary doping area is at least one line-shaped line, the line is crossed with the orthographic projection of at least one front electrode on the surface of the diffusion layer but not overlapped, and the ohmic contact of the secondary doping area and the front electrode is only at the crossed position.
2. The solar cell of claim 1, wherein: the line is one or any combination of a straight line, a broken line or a curve.
3. The solar cell of claim 2, wherein: the lines of each line are the same, and the spacing between adjacent lines is equal.
4. The solar cell of claim 1, wherein: the front electrode comprises a first electrode and a second electrode; the first electrodes are arranged on the first substrate, and each first electrode is crossed with at least one second electrode but not overlapped with the second electrode;
the lines intersect with but do not coincide with the orthographic projection of the at least one second electrode on the surface of the diffusion layer.
5. The solar cell of claim 4, wherein: the first electrode is a plurality of thick grid line electrodes which are parallel to each other, the second electrode is a plurality of thin grid line electrodes which are parallel to each other, and the second electrode is perpendicular to the first electrode.
6. The solar cell of claim 1, wherein: the solar cell is a BSF cell, a MWT cell, a PERC cell, a PERL cell, a PERT cell or a Topcon cell.
7. A method of manufacturing a solar cell according to any one of claims 1 to 6, comprising a diffusion step and an electrode manufacturing step, characterized in that: the method also comprises the following steps:
and (3) front secondary doping: and carrying out secondary doping on the diffusion layer with the front surface formed in the diffusion step to form a secondary doping area.
8. The method of claim 7, wherein: the secondary doping adopts a laser irradiation process, and the laser scans according to a laser irradiation path to form a secondary doping area.
9. The method of claim 8, wherein: the spot size of the laser focused on the surface of the diffusion layer is 30-500 μm.
10. The method of claim 7, wherein: the method specifically comprises the following steps:
s1, texturing the surface of the substrate;
s2, a diffusion step, wherein a diffusion layer and an oxidation layer are formed on the front surface of the substrate;
s3, front secondary doping: performing secondary doping on the diffusion layer with the front surface formed in the diffusion step to form a secondary doping area and reduce the sheet resistance of the secondary doping area;
s4, removing the oxide layer and the back junction and the side junction of the diffusion layer to insulate the front surface and the back surface;
s5, preparing a front antireflection layer;
s6, preparing a front electrode and a back electrode;
and S7, sintering to enable the front electrode to penetrate through the anti-reflection layer to form ohmic contact with the diffusion layer and the intersection of the secondary doping region, and enabling the back electrode to form ohmic contact with the substrate.
CN202011621865.1A 2020-12-31 2020-12-31 Solar cell and preparation method thereof Pending CN112838133A (en)

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