CN213150794U - Heterojunction solar cell and cell module - Google Patents

Abstract

The application provides a heterojunction solar cell and a cell module, and relates to the technical field of solar cells. The heterojunction solar cell comprises a silicon wafer, a passivation layer, a doping layer, a TCO film and a main body electrode, wherein the silicon wafer, the passivation layer, the doping layer and the TCO film are sequentially stacked, and the main body electrode is positioned on one side, far away from the doping layer, of the TCO film; the main body electrode includes: the device comprises a plurality of metal composite layers which are in contact with the TCO film and distributed at intervals, and a plurality of hot-pressing base metal wires which are distributed in parallel and positioned on one side of the metal composite layers, which is far away from the TCO film; the thickness of the metal composite layer is 2-50 nm. The hot-pressing base metal wire is base metal, and the cost is reduced. The thickness of the metal composite layer is only 2 to 50nm, and even if the metal composite layer contains a noble metal, the cost is low because the thickness is small. A hole is usually formed between the hot-pressing metal wire and the TCO film, the metal composite layer in the main body electrode is in direct contact with the TCO film, and the hot-pressing metal wire is in contact with the TCO film through the metal composite layer, so that the adhesion strength of the main body electrode and the TCO film is increased, the reliability of conductive connection is improved, and the contact resistance is reduced.

Description

Heterojunction solar cell and cell module

Technical Field

The utility model relates to a solar cell technical field especially relates to a heterojunction solar cell and battery pack.

Background

The heterojunction solar cell generally comprises a silicon wafer, a passivation layer, a doping layer, a Transparent Conducting Oxide (TCO) film, and a gate line on one side of the TCO film away from the doping layer, which are sequentially stacked.

At present, the grid line of the heterojunction solar cell is mainly made of low-temperature silver paste, specifically, the low-temperature silver paste is screen-printed on a TCO film, and then the grid line is obtained through drying and curing.

However, the grid lines in the heterojunction solar cell need to consume a large amount of low-temperature silver paste, which results in higher cost of the heterojunction solar cell.

SUMMERY OF THE UTILITY MODEL

The utility model provides a heterojunction solar cell and battery pack aims at solving a large amount of low temperature silver thick liquid of grid line consumption among the current heterojunction solar cell, leads to heterojunction solar cell's problem with high costs.

According to a first aspect of the present invention, a heterojunction solar cell is provided, which comprises a silicon wafer, a passivation layer, a doping layer, a TCO film, and a main electrode located on one side of the TCO film away from the doping layer, wherein the silicon wafer, the passivation layer, the doping layer, the TCO film and the main electrode are sequentially stacked;

the main body electrode includes: the metal composite layers are in contact with the TCO film at intervals, and the hot-pressing base metal wires are located on one side, far away from the TCO film, of the metal composite layers and distributed in parallel; the thickness of the metal composite layer is 2-50 nm;

and the projection of the metal composite layer is correspondingly superposed with the projection of the hot-pressing base metal wire.

Optionally, each metal composite layer consists of a low-resistance metal sub-film layer and a barrier contact base metal sub-film layer; wherein the low-resistance metal sub-film layer is in contact with the TCO film.

Optionally, the thickness of the low-resistance metal sub-film layer and the thickness of the barrier contact base metal sub-film layer are both 1-25 nm.

Optionally, the hot-pressed base metal wire is composed of a base metal wire and a low-temperature connecting layer wrapping the base metal wire.

Optionally, the thickness of hot-pressing base metal wire is 40-220um, and the thickness of base metal wire is 30-200 um.

Optionally, the low-temperature connection layer is a low-temperature alloy layer or anisotropic conductive adhesive.

Optionally, the low-resistance metal sub-film layer is a copper low-resistance sub-film layer and/or a silver low-resistance sub-film layer;

the barrier contact base metal sub-film layer is a nickel barrier contact sub-film layer and/or an aluminum barrier contact sub-film layer.

Optionally, the base metal wire is circular in cross-section in a direction perpendicular to the length.

Optionally, the base metal wire is a copper wire and/or an aluminum wire.

Optionally, the low-temperature alloy layer is a tin-bismuth alloy layer;

the anisotropic conductive adhesive is formed by metal particles and resin.

In the embodiment of the utility model, the heterojunction solar cell comprises a silicon wafer, a passivation layer, a doping layer, a TCO film and a main body electrode, wherein the silicon wafer, the passivation layer, the doping layer, the TCO film and the main body electrode are sequentially stacked; the main body electrode includes: the metal composite layers are in contact with the TCO film at intervals, and the hot-pressing base metal wires are located on one side, far away from the TCO film, of the metal composite layers and distributed in parallel; the thickness of the metal composite layer is 2-50nm, and the hot-pressing base metal wire is base metal, so that the cost is greatly reduced. Further, the thickness of the metal composite layer is only 2 to 50nm, and even if the metal composite layer contains a noble metal, the cost is low because of its small thickness. Meanwhile, a cavity usually exists between the hot-pressing metal wire and the TCO film, the metal composite layer in the main body electrode is directly contacted with the TCO film, and the hot-pressing metal wire is contacted with the TCO film through the metal composite layer, so that the problems of large resistance and poor adhesion caused by reduction of the contact area between the hot-pressing metal wire and the TCO film due to the cavity between the hot-pressing metal wire and the TCO film can be avoided, therefore, the adhesion strength between the main body electrode and the TCO film can be increased through the metal composite layer between the hot-pressing metal wire and the TCO film, the reliability of conductive connection is improved, and the contact resistance. The projection of the metal composite layer is correspondingly superposed with the projection of the hot-pressing base metal wire, and even if the metal composite layer is opaque, the metal composite layer is only positioned below the hot-pressing base metal wire, so that the rest part is not shielded, and the power of the heterojunction solar cell is not reduced.

According to a second aspect of the present invention, there is provided a battery module, comprising at least two heterojunction solar cells as described in any of the above, and a conductive connecting member;

the conductive connecting piece is in conductive connection with a first electrode of one heterojunction solar cell and a second electrode of an adjacent heterojunction solar cell, and the polarities of the first electrode and the second electrode are opposite.

The cell module has the same or similar beneficial effects as the heterojunction solar cell, and the details are not repeated herein to avoid repetition.

Drawings

In order to more clearly illustrate the technical solution of the embodiments of the present invention, the drawings required to be used in the description of the embodiments of the present invention will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive labor.

Fig. 1 shows a schematic structural diagram of a heterojunction solar cell in an embodiment of the invention;

fig. 2 shows a schematic view of a lamination of a bulk electrode and a TCO film in an embodiment of the present invention;

fig. 3 shows a top view of a heterojunction solar cell in an embodiment of the invention;

FIG. 4 shows a longitudinal cross-sectional view of a hot-pressed base metal wire in an embodiment of the invention;

figure 5 shows a transverse cross-sectional view of a hot-pressed base-metal wire in an embodiment of the invention.

Description of the figure numbering:

1-silicon chip, 2-passivation layer, 3-doping layer, 4-TCO film, 5-main body electrode, 51-metal composite layer, 52-hot-pressing base metal wire, 521-base metal wire, 522-low temperature connecting layer and M-cavity.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Referring to fig. 1, fig. 1 shows a schematic structural diagram of a heterojunction solar cell in an embodiment of the present invention, the heterojunction solar cell includes a silicon wafer 1, a passivation layer 2, a doping layer 3, a TCO film 4, and a main body electrode 5 located on one side of the TCO film 4 far from the doping layer 3, which are stacked in sequence. It should be noted that the doping types of the two doped layers on both sides of the silicon wafer 1 are opposite. For example, the doped layer 3 on the light-facing side of the silicon wafer 1 may be an n-type doped layer, and the doped layer 3 on the backlight side of the silicon wafer 1 may be a p-type doped layer. The heterojunction solar cell may be a silicon heterojunction solar cell.

The main body electrode 5 includes: a plurality of spaced apart metal composite layers 51 in contact with the TCO film 4, and a plurality of parallel hot pressed base wires 52 on the side of the metal composite layers 51 away from the TCO film 4. The thickness h1 of the metal composite layer 51 is 2 to 50nm (nanometers). The hot-pressing base metal wire 52 is a base metal, and compared with a grid line formed by low-temperature silver paste in the prior art, the cost is greatly reduced. Furthermore, the thickness h1 of the metal composite layer 51 is only 2-50nm, and even if the metal composite layer 51 contains noble metal, the size is smaller than that of a grid line of 10um (micrometer) or more, and therefore the cost is lower.

In the main electrode 5, the projection of each metal composite layer 51 is correspondingly overlapped with the projection of each hot-pressing base metal wire 52, and further, the metal composite layer 51 is opaque, and because the metal composite layer is only positioned below the hot-pressing base metal wires 52, the rest part is not shielded, and the power of the heterojunction solar cell is not reduced.

Meanwhile, referring to fig. 2, fig. 2 shows a schematic diagram of a lamination of a bulk electrode and a TCO film according to an embodiment of the present invention. Fig. 3 shows a top view of a heterojunction solar cell in an embodiment of the invention. Referring to fig. 2, a cavity M generally exists between the hot-pressing wire 52 and the TCO film 4, the metal composite layer 51 in the main electrode 5 directly contacts the TCO film 4, and the hot-pressing wire 52 contacts the TCO film 4 through the metal composite layer 51, so that the problems of large resistance and poor adhesion caused by the reduction of the contact area between the hot-pressing wire 52 and the TCO film 4 due to the cavity M between the hot-pressing wire 52 and the TCO film 4 can be avoided, and therefore, the adhesion strength between the main electrode 5 and the TCO film 4 can be increased through the metal composite layer 51 between the hot-pressing wire 52 and the TCO film 4, the reliability of conductive connection is improved, and the contact resistance is reduced. The TCO film and the main body electrode jointly form an electrode of the heterojunction solar cell.

Alternatively, each metal composite layer 51 is composed of a low-resistance metal sub-film layer and a barrier contact base metal sub-film layer. Wherein the low-resistance metal sub-film layer is in contact with the TCO film 4. The low-resistance metal sub-film layer is low in resistance, the low-resistance metal sub-film layer is in contact with the TCO thin film 4 and is mainly used for reducing transverse conduction resistance, and the low-resistance metal sub-film layer can better collect current to a position where the low-resistance metal sub-film layer is in contact with a hot-pressing metal wire subsequently. The component of the barrier contact base metal sub-film layer is mainly base metal, and the barrier contact base metal sub-film layer is mainly used for improving the contact strength with the hot-pressed metal wire and preventing the low-resistance metal sub-film layer from being oxidized.

Optionally, the low-resistance metal sub-film layer is a copper low-resistance sub-film layer and/or a silver low-resistance sub-film layer, and the low-resistance metal sub-film layer made of the material has low resistivity, so that the transverse conduction resistance is favorably reduced. Even if the low-resistance metal sub-film layer may be made of noble metal, the low-resistance metal sub-film layer is only 1-25nm thick, so that the cost is reduced more compared with the low-temperature silver paste grid line with the thickness of about 10um in the prior art.

Optionally, the barrier contact base metal sub-film layer is a nickel barrier contact sub-film layer and/or an aluminum barrier contact sub-film layer, and the barrier contact base metal sub-film layer made of the materials is beneficial to improving the contact strength with the hot-pressing metal wire and preventing the low-resistance metal sub-film layer from being oxidized. Meanwhile, the materials are base metals, so that the cost is low.

Optionally, the thickness of the low-resistance metal sub-film layer and the thickness of the barrier contact base metal sub-film layer are both 1-25nm, so that even though noble metal may be used in the low-resistance metal sub-film layer, the cost of the electrode is low due to the small size of the noble metal. And the low-resistance metal sub-film layer is in the thickness range, so that the resistance is low. The contact resistance base metal sub-film layer is in the thickness range, the contact strength with the hot-pressing metal wire is high, and the effect of preventing the low-resistance metal sub-film layer from being oxidized is good. The thickness may be a dimension in a direction parallel to the light-facing surface of the silicon wafer.

Figure 4 shows a longitudinal cross-sectional view of a hot-pressed base metal wire in an embodiment of the invention. Figure 5 shows a transverse cross-sectional view of a hot-pressed base-metal wire in an embodiment of the invention. The transverse cross-sectional view may be a cross-sectional view parallel to the light-facing surface of the silicon wafer. Alternatively, referring to fig. 4 and 5, the hot-pressed base metal wire 52 is composed of a base metal wire 521 and a low-temperature connection layer 522 wrapping the base metal wire 521. The low-temperature connection layer 522 is mainly used to make good electrical contact with the metal composite layer 51 or the barrier contact base metal sub-film layer in the metal composite layer 51 at a relatively low temperature, for example, 200 ℃. The low-temperature connecting layer 522 is adopted to realize good electrical contact with the metal composite layer 51 or the barrier contact base metal sub-film layer in the metal composite layer 51 at a lower temperature, and the performance of the heterojunction solar cell cannot be influenced.

Optionally, referring to fig. 4, the thickness h2 of the hot-pressed base metal wire 52 is 40-220um, the thickness of the low-temperature connection layer 522 is 10-20um, and the thickness of the base metal wire 521 is 30-200um, and the thickness ranges not only have good electrical contact, but also have conductivity and energy consumption, and reduce the resistance for collecting current.

Alternatively, as shown in FIG. 5, the base wire 521 has a circular cross-section in a direction perpendicular to its length for ease of manufacture. For example, in the direction perpendicular to the length, the base-wire 521 has a circular cross-section with a diameter of 30-200 um.

Optionally, the base metal wire 521 is a copper wire and/or an aluminum wire, and the base metal wire 521 made of the materials is beneficial to current collection. For example, the base metal wire 521 may be selected from copper wire.

Optionally, the low-temperature connection layer is a low-temperature alloy layer or an anisotropic conductive adhesive, and the low-temperature connection layer of the above materials is in good electrical contact with the metal composite layer 51 or the contact-blocking base metal sub-film layer in the metal composite layer 51 at a lower temperature, and the performance of the heterojunction solar cell is not affected.

Optionally, the low-temperature alloy layer is a tin-bismuth alloy layer, that is, the low-temperature alloy layer is an Sn-Bi alloy, and at a lower temperature, the low-temperature alloy layer is in good electrical contact with the metal composite layer 51 or the barrier contact base metal sub-film layer in the metal composite layer 51.

Optionally, the anisotropic conductive adhesive is a conductive adhesive composed of metal particles and resin, and at a lower temperature, the anisotropic conductive adhesive is in good electrical contact with the metal composite layer 51 or the barrier contact base metal sub-film layer in the metal composite layer 51.

The preparation method of the heterojunction solar cell can be as follows: (1) firstly, texturing and cleaning a silicon wafer 1; (2) the amorphous silicon passivation layers 2 are respectively deposited on two sides of the silicon wafer 1, the doped layers 3 are deposited on one side of the passivation layer 2 far away from the silicon wafer 1, the doped layers 3 on the two sides of the silicon wafer 1 are different in doping type, for example, the doped layer 3 on the light facing surface of the silicon wafer 1 can be an n-type doped layer, and the doped layer 3 on the backlight surface of the silicon wafer 1 can be a p-type doped layer. The silicon wafer 1, the passivation layer 2 and the doping layer 3 which are sequentially stacked form a core structure of the heterojunction solar cell, wherein the passivation layer 2 is responsible for passivating the surface of the silicon wafer 1, the n-type doping layer forms a field passivation layer, and the p-type doping layer forms an emitter.

And preparing an electrode on the basis of the core structure of the heterojunction solar cell. The electrode preparation steps are as follows: (1) depositing TCO films 4 on the front surface and the back surface of a core structure of the solar cell through an adjusting process; the adjusting process mainly aims to properly improve the conductive capability of the TCO film by adjusting process parameters. (2) Masking the front and back sides to deposit a plurality of parallel metal composite layers 51; (3) covering the surface of the base metal wire 521 with low-temperature alloy or anisotropic conductive adhesive to form a hot-pressing metal wire 52, the cross-sectional views of which are shown in fig. 4 and 5; (4) the hot-pressing wire 52 is directly hot-pressed on the metal composite layer 51. The preferred diameter of the hot-pressed wire 52 is 40-220 μm, and the temperature of the hot-pressing is preferably in the range of 150-250 ℃. The side view is shown in figure 1, and the top view is shown in figure 3.

The metal composite layer 51 is prepared by a preferred sputtering method, before sputtering, a mask plate is firstly placed on a core structure of the heterojunction solar cell plated with the TCO film layer 4, the core structure and the mask plate of the heterojunction solar cell are transmitted into a first sputtering cavity, a target material of the first sputtering cavity is low-resistance metal, preferably Cu, Ag and the like, and the sputtering is preferably carried out under the following conditions: the sputtering pressure is 0.3-0.7Pa, the DC sputtering power is 200-. And then transmitting the core structure and the mask of the heterojunction solar cell into a second sputtering cavity, wherein the target of the second sputtering cavity is high-adhesion and anti-oxidation metal, namely barrier contact metal, preferably Ni, Al and the like, and the sputtering is preferably carried out under the following conditions: the sputtering pressure is 0.3-0.7Pa, the DC sputtering power is 200-. And after the preparation, the metal composite layer is conveyed out of the second sputtering cavity, and the mask is removed to finish the preparation of the metal composite layer.

The utility model also provides a battery pack, this battery pack include two at least heterojunction solar cells as before, electrically conductive connecting piece, and the first electrode of a heterojunction solar cell and adjacent heterojunction solar cell's second electrode are connected to electrically conductive connecting piece electrically conductive, and the polarity of this first electrode and this second electrode is opposite. In the cell module, reference may be made to the above description of the heterojunction solar cell, and the same or similar advantageous effects may be achieved.

The embodiments of the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, which are only illustrative and not restrictive, and those skilled in the art can make many forms without departing from the spirit and scope of the present invention, and all of them fall within the protection scope of the present invention.

Claims (11)

1. The heterojunction solar cell is characterized by comprising a silicon wafer, a passivation layer, a doping layer, a TCO film and a main body electrode, wherein the silicon wafer, the passivation layer, the doping layer, the TCO film and the main body electrode are sequentially stacked;

the main body electrode includes: the metal composite layers are in contact with the TCO film at intervals, and the hot-pressing base metal wires are located on one side, far away from the TCO film, of the metal composite layers and distributed in parallel; the thickness of the metal composite layer is 2-50 nm;

and the projection of the metal composite layer is correspondingly superposed with the projection of the hot-pressing base metal wire.

2. The heterojunction solar cell of claim 1, wherein each of the metal composite layers consists of a low resistance metal sub-film layer and a barrier contact base metal sub-film layer; wherein the low-resistance metal sub-film layer is in contact with the TCO film.

3. The heterojunction solar cell of claim 2, wherein the thickness of each of said low resistance metal sub-film layer and said barrier contact base metal sub-film layer is 1-25 nm.

4. The heterojunction solar cell of claim 1 or 2, wherein the hot-pressed base-metal wires consist of base-metal wires and a low-temperature connection layer encasing the base-metal wires.

5. The heterojunction solar cell of claim 4, wherein the thickness of the hot-pressed base-metal wires is 40-220um and the thickness of the base-metal wires is 30-200 um.

6. The heterojunction solar cell of claim 4, wherein the low temperature connection layer is a low temperature alloy layer or an anisotropic conductive paste.

7. The heterojunction solar cell of claim 2, wherein the low resistance metal sub-film layer is a copper low resistance sub-film layer and/or a silver low resistance sub-film layer;

the barrier contact base metal sub-film layer is a nickel barrier contact sub-film layer and/or an aluminum barrier contact sub-film layer.

8. The heterojunction solar cell of claim 4, wherein the cross-section of the base-metal wires is circular in a direction perpendicular to the length.

9. A heterojunction solar cell according to claim 4, wherein the base metal wires are copper and/or aluminium wires.

10. The heterojunction solar cell of claim 6, wherein the low temperature alloy layer is a tin-bismuth alloy layer.

11. A cell assembly comprising at least two heterojunction solar cells according to any of claims 1 to 10, an electrically conductive connection;

the conductive connecting piece is in conductive connection with a first electrode of one heterojunction solar cell and a second electrode of an adjacent heterojunction solar cell, and the polarities of the first electrode and the second electrode are opposite.

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