CN217881527U - Novel electrode of solar cell - Google Patents

Abstract

The utility model relates to a novel electrode of a solar cell, which comprises a copper wire, wherein the surface of the copper wire is also coated with a metal coating, and the surface of the metal coating is also attached with a silver paste layer; the metal coating is made of a unitary metal material, a binary alloy material, a ternary alloy material or more complex alloy materials; the unitary metal material is any one of Ag, sn, ni, au, bi and the like; the binary alloy material is any one of Sn-Pb, sn-Zn, sn-Bi, sn-Au and the like; the ternary alloy material is any one of Sn-Ag-Sb, sn-Ag-Bi and the like; the utility model discloses the solar cell electrode of preparation can reduce solar cell's series resistance, reduces solar cell's electrode cost to can satisfy the requirement of solar cell electrode adhesive force.

Description

Novel electrode of solar cell

Technical Field

The utility model relates to a novel electrode of solar cell.

Background

The solar cell is a photoelectric transducer made by utilizing photovoltaic effect, and can directly convert solar energy into electric energy. The variety of solar cells is wide, and at present, over 95% of the solar cells are prepared by using silicon-based sheets, and the industrialization mainly includes PERC solar cells, TOPCon solar cells, HJT solar cells and the like. Regardless of any solar cell, the solar cell can be divided into a substrate and an electrode according to the functions performed by the solar cell, wherein the main functions of the substrate are light absorption, carrier generation and separation; the main function of the electrodes is to conduct out the photo-generated carriers. The substrate of a solar cell is typically a semiconductor material and the electrodes are typically metals or metal oxides. The most common metal used today is silver paste made from silver, which is sintered and bonded to a base material to form the metal electrode of the cell. Because the base material and the electrode of the solar cell are two materials with completely different properties, a low ohmic contact is required to be formed and a certain peeling strength is required to meet the service life of the solar cell for more than 25 years outdoors in the process of preparing the electrode of the solar cell.

Through years of efforts of researchers, at present, a metal electrode is mainly prepared on a silicon-based sheet solar cell by adopting silver paste printing and sintering.

The silver paste used for the electrode material of the solar cell at present mainly has the following problems:

1. silver paste is expensive, the non-silicon cost of the cell slice accounts for about 30-40%, and the overall cost of the cell slice accounts for about 8-10%; the silver powder accounts for 98% of the cost of the silver paste raw material on the front surface of the cell, so that the silver paste is adopted to prepare the electrode of the solar cell, which is not beneficial to continuously reducing the photovoltaic power generation cost.

2. The global total reserve of silver is about 40 ten thousand tons, and if the new photovoltaic increasing machines of 2021-2023 are 160GW, 200GW and 240GW, the total required amount of the photovoltaic silver paste in 2021-2023 is expected to reach 3500 ton, 4300 ton and 5000 ton; solar photovoltaic power generation becomes the main power of human energy in the future, so all global silver can not meet the requirement at all.

Researchers have tried a number of methods to reduce the consumption of silver in solar cells or to replace silver with another metal, typically silver-coated copper powderOr electroplating copper and other metals, but the chemical property of the superfine copper powder is much more active than that of silver, and the superfine copper powder is easy to oxidize, and Cu is generated on the surface of copper after oxidation ₂ O and CuO films, and the finer the granularity of the copper powder is, the larger the specific surface area of the copper powder is, and the faster the oxidation speed is; if the proportion of silver in the silver-coated copper powder is too low, an electrode with low resistance cannot be formed in a solar cell sintering process due to copper oxidation, so that the efficiency of the solar cell is reduced; if the proportion of silver in the silver-coated copper powder is large enough, the protection of silver can meet the requirement that copper is not oxidized in the subsequent sintering, but the high silver content cannot meet the requirement of reducing the cost; if the electroplating method is used to plate copper on a seed layer such as silver, however, because of the high electroplating cost and pollution, the two methods cannot be industrialized at present, and a solution is needed.

SUMMERY OF THE UTILITY MODEL

In order to overcome the shortcoming of the prior art, the utility model provides a novel electrode of solar cell specifically as follows:

the utility model provides a technical scheme that above-mentioned technical problem adopted does: a novel electrode of a solar cell is characterized in that: the copper wire comprises a copper wire, wherein the surface of the copper wire is further coated with a metal coating, and the surface of the metal coating is further adhered with a silver paste layer; the metal coating is made of a unitary metal material, a binary alloy material, a ternary alloy material or more complex alloy materials; the unitary metal material is any one of Ag, sn, ni, au and Bi; the binary alloy material is any one of Sn-Pb, sn-Zn, sn-Bi and Sn-Au; the ternary alloy material is any one of Sn-Ag-Sb and Sn-Ag-Bi.

Further, the cross-sectional shape of the copper wire is circular, rectangular, triangular or other regular and irregular shapes.

Further, the thickness of the metal coating is 1 um-10 um.

Compared with the prior art, the utility model has the advantages of:

(1) The resistivity of copper at 20 ℃ is 1.70X 10 ^-6 Omega cm, resistivity of silver is 1.47X 10 ^-6 Omega cm, therefore, the solar battery electrode can not be increased by using the utility modelThe series resistance of the electrode does not reduce the photoelectric conversion efficiency of the solar cell by replacing the conventional solar cell electrode with the electrode.

(2) Because there are front silver thick liquid and back silver thick liquid to adhere to on the copper wire surface to can carry out the alloying through sintering process and silicon, again because all contain bonding phase (glass powder) in current front silver thick liquid and the back silver thick liquid, consequently the utility model discloses can satisfy the requirement of solar cell electrode adhesive force.

(3) Because the front silver paste and the back silver paste are adhered to the surface of the copper wire, the silver-silicon alloy is formed in the subsequent alloying process, and therefore, the low ohmic contact can be formed with the cell matrix material.

(4) Since the copper wire is dip-plated or electroplated with any one of the unitary metal materials of Ag, sn, ni, au, bi and the like, or with any one of the binary alloy materials of Sn-Pb, sn-Zn, sn-Bi, sn-Au and the like, or with any one of the ternary alloy materials of Sn-Ag-Sb, sn-Ag-Bi and the like, or with more, the electroplated layer can completely cover the copper, so that the copper is not oxidized during sintering.

Drawings

Fig. 1 is a sectional view of a novel solar cell electrode according to the present invention.

Fig. 2 is a sectional structure diagram of an electrode for manufacturing a conventional aluminum back surface field solar cell, in which 1 is a copper wire, 2 is a plated Sn-Pb alloy, 3 is a front silver paste, 4 is an antireflection film of a solar cell, 5 is a phosphorus-doped n-type layer, 6 is a p-type single crystal silicon substrate, 7 is an aluminum back surface field, 8 is aluminum, 9 is a back surface silver paste, 10 is a plated Sn-Pb alloy, and 11 is a copper wire.

Fig. 3 is a sectional structure diagram of an electrode for manufacturing a PERC solar cell, in which 1 is a copper wire, 2 is electroplated Ag,3 is front silver paste, 4 is an antireflection film SiN of the solar cell, 5 is a phosphorus-doped n-type layer, 6 is a p-type crystalline silicon substrate, 7 is alumina, 8 is SiN,9 is back silver paste, 10 is electroplated Ag, and 11 is a copper wire.

FIG. 4 is a cross-sectional structure diagram of the electrode for preparing the HJT solar cell, in which 1 is a copper wire, 2 is electroplated SnSr,3 is a resin type low temperature silver paste, 4 is a front transparent conductive thin film (TCO), 5 is a p-type amorphous silicon layer (p-a-Si: H), 6 is an intrinsic amorphous silicon layer (i-a-Si: H), 7 is an n-type crystalline silicon layer (n-c-Si), 8 is an intrinsic amorphous silicon layer (i-a-Si: H), 9 is an n-type amorphous silicon layer (n-a-Si: H), 10 is a back transparent conductive thin film (TCO), 11 is a resin type low temperature silver paste, 12 is an electroplated SnSr, and 13 is a copper wire.

Fig. 5 is a cross-sectional structural view of an electrode for manufacturing an IBC solar cell, in which 1 is an SiN antireflection film, 2 is an n + layer having a doping concentration greater than that of n-type silicon, 3 is an n-type silicon substrate, 4 is a p-type diffusion layer, 5 is an n + layer having a doping concentration greater than that of n-type silicon, 6 is silicon oxide, 7 is silver paste, 8 is electroplated SnBi, and 9 is a copper wire.

Fig. 6 is a sectional structure diagram of TOPCon solar cell electrode preparation, in which 1 is copper wire, 2 is electroplated SnSr,3 is front silver paste, 4 is SiN antireflection film, 5 is AlO passivation film, 6 is p-type doping layer, 7 is n-type crystalline silicon substrate (n-c-Si), 8 is silicon oxide thin film, 9 is polycrystalline silicon thin film, 10 is SiN passivation film, 11 is silver paste, 12 is electroplated SnSr, and 13 is copper wire.

FIG. 7 is a cross-sectional structural diagram of an electrode for preparing an HBC solar cell, wherein 1 in the diagram is an antireflection film, 2 is an intrinsic amorphous silicon layer (i-a-Si: H), 3 is an n-type crystalline silicon layer (n-c-Si) resin type low-temperature silver paste, 4 is an intrinsic amorphous silicon layer (i-a-Si: H), 5 is a p-type amorphous silicon layer (p-a-Si: H), 6 is an n-type amorphous silicon layer (n-a-Si: H), 7 is a transparent conductive film (TCO), 8 is an adhered low-temperature silver paste, 9 is electroplated SnSr, and 10 is a copper wire.

Detailed Description

Unless defined otherwise, technical or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the description herein do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.

To maintain the following description of the embodiments of the present invention clear and concise, detailed descriptions of well-known functions and components may be omitted.

As shown in fig. 1, the novel electrode for the solar cell comprises a copper wire 1, wherein a metal coating layer 2 is further coated on the surface of the copper wire 1, and a silver paste layer 3 is further attached to the surface of the metal coating layer 2; the metal coating 2 is made of a unitary metal material, a binary alloy material, a ternary alloy material or more complex alloy materials; the unitary metal material is any one of Ag, sn, ni, au and Bi; the binary alloy material is any one of Sn-Pb, sn-Zn, sn-Bi and Sn-Au; the ternary alloy material is any one of Sn-Ag-Sb and Sn-Ag-Bi.

The cross section of the copper wire 1 is round, rectangular, triangular or other regular and irregular shapes.

The thickness of the metal plating layer 2 is 1 um-10 um.

The preparation method of the electrode comprises the following steps:

the first embodiment is as follows: preparation of novel alloy electrode on conventional aluminum back surface field solar cell

As shown in fig. 2, the silicon wafer for manufacturing the crystalline silicon solar cell is first sorted, and the thickness, minority carrier lifetime, surface flatness, presence or absence of micro cracks, resistivity, surface oil stains and the like of the silicon wafer are mainly inspected.

And secondly, texturing and cleaning, wherein in the texturing, the monocrystalline silicon wafer with the (100) crystal face is subjected to anisotropic corrosion by adopting a mixed solution of alkali and a texturing additive, and a pyramid-shaped textured structure is formed on the surface, so that the absorption of the silicon wafer on incident sunlight is effectively enhanced.

Diffusion and junction formation are carried out after texturing, and the main purpose of diffusion is to manufacture a heart pn junction of the solar cell.

Parasitic pn junctions exist on the back surface and the side surface of the diffused silicon wafer, so that the pn junctions on the back surface and the edge are removed by adopting wet etching equipment to remove n-type regions on the back surface and the side surface.

Preparing an antireflection film on the silicon wafer with the pn junction removed from the back and the edge by adopting plasma enhanced chemical vapor deposition, wherein the used reaction gases are silane and ammonia gas, and SiNx with the wavelength of about 70nm is formed on the surface of the silicon wafer: and the H layer plays a role in surface antireflection and passivation.

Then, according to the utility model discloses a plated Sn-Pb copper wire adopt to knit bars machine and pull, adhere to a thin layer back silver thick liquid on the copper wire that has plated metallic alloy behind the back silver thick liquid that knits bars machine earlier, will be stained with the metal wire of back silver thick liquid and place the back at the battery piece as required and dry, the upset.

And then drawing the copper wire through front silver paste on the grid weaving machine by using a grid weaving machine, attaching a thin layer of front silver paste on the copper wire plated with the metal alloy, placing the metal wire adhered with the front silver paste on the front of the battery piece according to requirements for drying, sintering in a high-temperature sintering furnace to form a metal electrode with certain binding force with silicon, and finally sorting the electrical property and the like of the battery piece.

Example two: preparation of novel alloy electrode on PERC solar cell

As shown in fig. 3, the silicon wafers for manufacturing the crystalline silicon solar cell are first sorted, and the thickness, minority carrier lifetime, surface flatness, presence or absence of micro cracks, resistivity, surface oil stains, and the like of the silicon wafers are mainly inspected.

And secondly, texturing and cleaning, wherein in the texturing, the monocrystalline silicon wafer with the (100) crystal face is subjected to anisotropic corrosion by adopting a mixed solution of alkali and a texturing additive, and a pyramid-shaped textured structure is formed on the surface.

And (5) carrying out phosphorus diffusion and knot making after wool making.

Parasitic pn junctions exist on the back surface and the side surface of the diffused silicon wafer, so that the pn-type regions on the back surface and the side surface are removed, and wet etching equipment is adopted to remove the pn junctions on the back surface and the edge.

Depositing a layer of aluminum oxide on the silicon chip with the pn junction on the back and the edge removed by adopting an atomic layer, and preparing SiN on the aluminum oxide by adopting plasma enhanced chemical vapor deposition _X Reaction gas usedSilane and ammonia gas are used, and finally, a SiNx layer with the thickness of about 70nm is formed on the other surface of the silicon wafer, so that the effects of surface antireflection and passivation are achieved.

And then, ablating the aluminum oxide and SiNx composite film on the back by using laser, forming an aluminum grid line in an ablation area by adopting a screen printing method after ablation is finished, and drying.

And then according to the utility model discloses a plated Sn-Ag-Sb copper wire adopt to weave bars machine and pull, adhere to a thin layer back silver thick liquid on the copper wire that has plated metallic alloy behind the back silver thick liquid that weaves bars machine earlier, will be stained with the metal wire of back silver thick liquid and place the back at the battery piece as required and dry, the upset.

And then, drawing the copper wires by using a grid weaving machine to pass through front silver paste on the grid weaving machine, attaching a thin layer of front silver paste on the copper wires plated with Sn-Ag-Sb metal alloy, placing the metal wires adhered with the front silver paste on the front of the battery piece according to requirements for drying, sintering in a high-temperature sintering furnace to form a metal electrode with certain binding force with silicon, and finally sorting the electrical property and the like of the battery piece.

Example three: preparing novel alloy electrode on HJT solar cell

As shown in fig. 4, firstly, an n-type crystalline silicon wafer is selected, chemically cleaned and textured, then an intrinsic amorphous silicon layer is deposited on one surface of the n-type crystalline silicon wafer by using a PECVD process, a p-type amorphous silicon layer is deposited on the other surface of the n-type crystalline silicon wafer, an intrinsic amorphous silicon layer and an n-type amorphous silicon layer are deposited on the other surface of the n-type crystalline silicon wafer, transparent conductive films (TCO films) are respectively manufactured on two surfaces of the cell wafer by using a sputtering method after deposition, then the copper wire plated with SnSr is pulled by using a grid weaving machine, a thin silver paste is adhered on the copper wire plated with metal alloy after passing through resin type low-temperature slurry on the grid weaving machine, and the metal wire adhered with the silver paste is placed on the transparent conductive film on one surface of the cell wafer according to requirements for drying and turning.

And then, drawing the copper wire by using a grid weaving machine through resin type low-temperature silver paste on the grid weaving machine, attaching a thin layer of silver paste on the SnSr-plated metal alloy copper wire, placing the metal wire adhered with the silver paste on the other side of the battery piece according to requirements, drying, sintering in a low-temperature sintering furnace, forming a metal electrode with a certain binding force with the transparent conductive film, and finally sorting the electrical property and the like of the battery piece.

Example four: preparation of novel alloy electrode on IBC solar cell

As shown in fig. 5, an n-type crystal silicon wafer is selected, chemically cleaned and textured, a boron source is printed on the back surface of the n-type crystal silicon wafer, the n-type crystal silicon wafer is dried, boron-phosphorus co-diffusion is performed, phosphorosilicate glass is removed, silicon oxide is formed by oxidation at high temperature, and a SiN antireflection layer is deposited on the front surface of the battery by using a PECVD process.

And finally, photoetching silicon oxide on the back of the battery, respectively forming metal contact windows on the n-type diffusion layer and the p-type diffusion layer on the back of the battery, drawing the SnBi-plated copper wire by using a grid weaving machine, adhering a thin silver paste layer on the copper wire plated with the metal alloy after passing through the paste on the grid weaving machine, placing the metal wire adhered with the silver paste on the corresponding position of the battery piece according to requirements, drying, sintering, and finally sorting the performances of the battery piece.

Example five: preparation of novel alloy electrode on TOPCon solar cell

As shown in fig. 6, an n-type crystalline silicon wafer is selected firstly, is chemically cleaned and is subjected to texturing, boron diffusion is performed at a high temperature to form a p-type layer, a pn junction is formed, the edge and the pn junction on the back of the battery are corroded by a wet method, a silicon oxide film grows on the n-type layer on the back, a polycrystalline silicon film is deposited on the silicon oxide, an AlO film is deposited on the silicon oxide film on the front of the battery, siN films are deposited on two sides of the battery respectively, ablation slotting is performed on the front of the battery by using laser to form a metal contact window, the copper wire plated with SnBi is pulled by a grid weaving machine, a thin silver paste layer is attached to the copper wire plated with metal alloy after passing through the paste on the grid weaving machine, and the metal wire adhered with the silver paste is placed on the opened groove of the battery to be dried and turned over according to requirements. And then, drawing the copper wire by using a grid weaving machine to pass through silver paste on the grid weaving machine, attaching a thin layer of silver paste on the SnBi-plated metal alloy copper wire, placing the metal wire adhered with the silver paste on the corresponding position on the back of the battery according to requirements, drying, sintering, and finally sorting the performance of the battery piece.

Example six: preparation of novel alloy electrode on HBC battery

As shown in fig. 7, an n-type crystalline silicon wafer is firstly selected, chemically cleaned and subjected to texturing, an intrinsic amorphous silicon layer is firstly deposited on two sides of the n-type crystalline silicon by a PECVD process, an SiN antireflection film is then deposited on the light facing side of the cell, an n-type amorphous silicon layer and a p-type amorphous silicon layer are respectively deposited on the intrinsic amorphous silicon layer on the other side of the cell, then a transparent conductive film (TCO film) is respectively prepared on the n-type amorphous silicon layer and the p-type amorphous silicon layer by a sputtering method, then the copper wire plated with SnSr is pulled by a grid weaving machine, a thin layer is attached to the copper wire plated with metal alloy after resin type low-temperature slurry on the grid weaving machine, the metal wire adhered with silver paste is placed on the transparent conductive film of the cell sheet according to requirements for drying, then sintered in a low-temperature sintering furnace, a metal electrode with certain binding force is formed by the transparent conductive film, and finally the performance of the cell sheet is sorted.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions described in the foregoing embodiments may be modified or some technical features may be equally replaced; such modifications or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (3)

1. A novel electrode of a solar cell is characterized in that: the copper wire comprises a copper wire, wherein the surface of the copper wire is also coated with a metal coating, and the surface of the metal coating is also adhered with a silver paste layer; the metal coating is made of a unitary metal material, a binary alloy material, a ternary alloy material or more complex alloy materials; the unitary metal material is any one of Ag, sn, ni, au and Bi; the binary alloy material is any one of Sn-Pb, sn-Zn, sn-Bi and Sn-Au; the ternary alloy material is any one of Sn-Ag-Sb and Sn-Ag-Bi.

2. The novel electrode of the solar cell as claimed in claim 1, wherein: the cross section of the copper wire is in a circular shape, a rectangular shape, a triangular shape or other regular and irregular shapes.

3. The novel electrode of claim 1, wherein: the thickness of the metal coating is 1 um-10 um.

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