CN116247107A

CN116247107A - Solar cell, preparation method and photovoltaic module

Info

Publication number: CN116247107A
Application number: CN202310246937.6A
Authority: CN
Inventors: 谢明辉; 李文琪; 陈一帆; 张国春
Original assignee: Zhejiang Jinko Solar Co Ltd; Jinko Solar Co Ltd
Current assignee: Zhejiang Jinko Solar Co Ltd; Jinko Solar Co Ltd
Priority date: 2023-03-09
Filing date: 2023-03-09
Publication date: 2023-06-09

Abstract

The embodiment of the application relates to the field of solar cells, and provides a solar cell, a preparation method and a photovoltaic module, wherein the solar cell comprises: a substrate; the conductive layer is positioned on the substrate; the functional film is positioned on the surface of the conductive layer; at least one electrode, each of the at least one electrode extending in a first direction; wherein each of the electrodes comprises: a main body portion located at a side of the functional film away from the substrate and extending in the first direction; a plurality of via portions spaced apart along the first direction, each of the plurality of via portions penetrating through the functional film and having one end in electrical contact with the main body portion and the other end in electrical connection with the conductive layer; wherein each of the via portions includes a plurality of connection portions penetrating the functional film, the plurality of connection portions being dispersed and discontinuous with each other. The solar cell provided by the application can at least improve the photoelectric conversion efficiency of the solar cell.

Description

Solar cell, preparation method and photovoltaic module

Technical Field

The embodiment of the application relates to the field of solar cells, in particular to a solar cell, a preparation method and a photovoltaic module.

Background

The causes affecting the performance of the solar cell (e.g., photoelectric conversion efficiency) include optical losses including reflection losses at the front surface of the cell, shadow losses in contact with the gate line, and non-absorption losses in the long band, etc., as well as electrical losses including losses in the semiconductor surface and in vivo photo-generated carrier recombination, contact resistance of the semiconductor and metal gate line, contact resistance of the metal and semiconductor, etc.

In order to reduce the contact resistance between the electrode and the semiconductor, the laser grooving is utilized in the process of preparing the battery, the surface recombination rate of the semiconductor is reduced through a point contact mode, and the reflection performance is improved, so that the open-circuit voltage of the battery is improved. However, in the laser grooving process, the existence of the passivation layer on the battery needs to be overcome, and laser grooving is performed on the surface of the substrate to locally remove the film layer of the passivation layer, so as to form an electrode contact region. The pattern of the laser grooves affects the surface field contact area and thus the electrical performance of the battery. Generally, the smaller the area of the electrode contact area is, the larger the passivation area of the surface field is, so that the surface recombination rate of the electrode and the semiconductor is reduced, and the short-circuit current and the open-circuit voltage are improved more. However, too small a surface field contact area may affect the area of the electrode, thereby affecting the photoelectric conversion efficiency of the solar cell.

Disclosure of Invention

The embodiment of the application provides a solar cell, a preparation method and a photovoltaic module, which are at least beneficial to improving the photoelectric conversion efficiency of the solar cell.

According to some embodiments of the present application, an aspect of embodiments of the present application provides a solar cell, including: a solar cell, comprising: a substrate; a conductive layer on the substrate; the functional film is positioned on the surface of the conductive layer; at least one electrode, each of the at least one electrode extending in a first direction; wherein each of the electrodes comprises: a main body portion located at a side of the functional film away from the substrate and extending in the first direction; a plurality of via portions spaced apart along the first direction, each of the plurality of via portions penetrating through the functional film and having one end in electrical contact with the main body portion and the other end in electrical connection with the conductive layer; wherein each of the via portions includes a plurality of connection portions penetrating the functional film, the plurality of connection portions being dispersed and discontinuous with each other.

In some embodiments, a ratio Q of the first area to the second area satisfies 10% < Q < 100%, the first area is a total orthographic projection area of bottoms of the plurality of connection portions on the surface of the conductive layer, and the second area is an orthographic projection area of an area surrounded by at least three connection portions on the outermost side in the via portion on the surface of the conductive layer.

In some embodiments, a ratio of a third area to the first area is less than 38%, the third area being an orthographic projected area of a bottom of each of the plurality of connections on the surface of the conductive layer.

In some embodiments, a first ratio Q1 of one of the via portions is different from a second ratio Q2 of another of the via portions.

In some embodiments, along the first direction, a second area of the via portion near the edge of the main body portion is smaller than a fourth area, where the fourth area is an orthographic projection area of an area surrounded by at least three connection portions on the outermost side of the via portion corresponding to the middle position of the main body portion on the surface of the conductive layer.

In some embodiments, the width of the via portion is less than or equal to the width of the body portion corresponding thereto in the second direction; wherein the second direction is perpendicular to the first direction.

In some embodiments, the width of the via portion in the second direction ranges from 3 μm to 5 μm.

In some embodiments, along the first direction, a first pitch is less than 4 times L, where the first pitch is a pitch of two adjacent via portions, and L is a length of the via portion in the first direction.

In some embodiments, the second pitch is greater than a third pitch along the first direction, the second pitch being a pitch of two adjacent via portions near the body portion edge, and the third pitch being a pitch of any adjacent two via portions other than the two adjacent via portions near the body portion edge.

In some embodiments, the order of arrangement of the plurality of connection portions of any one of the via portions is different from the order of arrangement of the plurality of connection portions of another one of the via portions.

In some embodiments, the orthographic projection shape of the connection part on the surface of the conductive layer is an irregular pattern.

In some embodiments, each of the electrodes further comprises: and the extending parts are positioned in the conductive layer, and each extending part is opposite to and in contact with one connecting part of the plurality of connecting parts.

According to some embodiments of the present application, another aspect of embodiments of the present application further provides a method for manufacturing a solar cell, including: providing a substrate; forming a conductive layer, wherein the conductive layer is positioned on the substrate to form an original film layer, and the original film layer is positioned on the surface of the conductive layer; grooving the original film layer to form a mold opening pattern, wherein the mold opening pattern comprises a processing part and a plurality of grooves, each groove of the plurality of grooves penetrates through the original film layer, the processing part is positioned between every two grooves of the plurality of grooves, and the rest of the original film layer and the processing part are used as functional films; the conductive material fills the plurality of grooves and is positioned on part of the functional film, the conductive material positioned in each groove of the plurality of grooves is used as a connecting part, the conductive material positioned on part of the functional film is used as a main body part, the main body part extends along a first direction, a plurality of connecting parts form a via hole part, and the via hole part is contacted with the main body part; the plurality of connection portions and the main body portion together constitute an electrode.

In some embodiments, the grooving process includes laser processing, etching a slurry, or ion etching.

In some embodiments, forming the open mold pattern includes: and arranging a processing model on the surface of the original film layer, wherein the processing model corresponds to the die opening pattern, grooving the partial area of the processing model to form grooves, taking the original film layer in the processing model which is not subjected to grooving as a processing part, and forming the die opening pattern by the processing part and the grooves.

In some embodiments, the grooving process is a laser process, and the process parameters of the laser process include: the laser power is 12% -16%; the laser frequency is 800 KHZ-12000 KHZ.

According to some embodiments of the present application, a further aspect of embodiments of the present application further provides a photovoltaic module, including: a cell string formed by connecting a plurality of solar cells as described in any one of the above embodiments, or a solar cell prepared by the method for preparing a plurality of solar cells as described in any one of the above embodiments; the packaging layer is used for covering the surface of the battery string; and the cover plate is used for covering the surface of the packaging layer, which is away from the battery strings.

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 electrode comprises a plurality of via hole parts and a main body part, each via hole part comprises a plurality of connecting parts penetrating through the functional film, and the connecting parts are dispersed and discontinuous. Through setting up discontinuous connecting portion, reduce the single via hole portion area that contains a plurality of connecting portions, reduced the area of the recess that forms in the functional film that single via hole portion corresponds, reduced the damage area of functional film to the integrality of functional film has been guaranteed to a certain extent, has promoted solar cell's open circuit voltage. The connecting parts which are scattered and discontinuous are arranged, the area of a local slotting area for accommodating the connecting parts is reduced, damage to the film layers around the slotting area is reduced, the appearance integrity of the film layers of the slotting area is good, the solar cell is enabled to have the possibility of repairing in the subsequent heat treatment process, and then the open-circuit voltage of the solar cell is improved.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, which are not to be construed as limiting the embodiments unless specifically indicated otherwise; in order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the drawings that are required to be used in the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person of ordinary skill in the art.

Fig. 1 is a schematic structural diagram of a solar cell according to an embodiment of the present disclosure;

FIG. 2 is a schematic view of a first cross-sectional structure of FIG. 1 along the line a1-a 2;

FIG. 3 is a schematic view of a second cross-sectional structure taken along the line a1-a2 in FIG. 1;

FIG. 4 is an enlarged view of a portion of FIG. 1 at A;

fig. 5 is a schematic view of a first structure of a via portion in a solar cell according to an embodiment of the present disclosure;

fig. 6 is a schematic view of a second structure of a via portion in a solar cell according to an embodiment of the present disclosure;

fig. 7 is a schematic view of a second structure of a solar cell according to an embodiment of the present disclosure;

fig. 8 is a schematic view of a third structure of a solar cell according to an embodiment of the present disclosure;

FIG. 9 is a schematic diagram of a solar cell according to an embodiment of the present disclosure;

fig. 10 is a schematic cross-sectional view of a solar cell according to an embodiment of the present disclosure;

fig. 11 is a schematic diagram of a second cross-sectional structure of a solar cell according to an embodiment of the present disclosure;

fig. 12 to 14 are schematic cross-sectional structures of solar cells corresponding to each step in a method for manufacturing a solar cell according to an embodiment of the present disclosure;

FIG. 15 is an electron microscope image of a conductive layer in a solar cell according to an embodiment of the present disclosure;

Fig. 16 is a schematic structural diagram of a photovoltaic module according to an embodiment of the present disclosure.

Detailed Description

As known from the background art, the photoelectric conversion efficiency of the current solar cell is poor.

Analysis finds that one of the reasons for the poor photoelectric conversion efficiency is that a conventional laser grooving process is generally to provide linear notches, a certain interval is arranged between the notches, the passivation efficiency of the battery and the series resistance of the battery are macroscopically regulated and controlled through regulating the ratio relation between the length of the notches and the interval, however, the characteristic size of the linear notches leads to smaller area of the notches, so that the situation that the electrode falls off due to insufficient binding force of an electroplated electrode or an aluminum hole phenomenon caused by that silver paste material forming the electrode cannot fill the linear notches may exist. Another scheme of laser grooving is to set up a plurality of big grooves which are arranged at intervals, the line width of the big grooves is substantially equal to the line width of the electrode, so that grooving treatment is required to be carried out on the area where the big grooves are located for many times in order to realize the shape requirement of the big grooves, and therefore, defects are caused on passivation layers around the big grooves, and the passivation effect of the passivation layers is further affected.

In the technical scheme provided by the embodiment of the application, each via hole part comprises a plurality of connecting parts penetrating through the functional film, and the connecting parts are dispersed and discontinuous with each other. Through setting up discontinuous connecting portion, reduce the single via hole portion area that contains a plurality of connecting portions, reduced the area of the recess that forms in the functional film that single via hole portion corresponds, reduced the damage area of functional film to the integrality of functional film has been guaranteed to a certain extent, has promoted solar cell's open circuit voltage. The connecting parts which are distributed and discontinuous are arranged, the area of a local slotting area for accommodating the connecting parts is reduced, damage to the film layers around the slotting area is reduced, the appearance integrity of the film layers of the slotting area is good, the solar cell is enabled to have the possibility of repairing in the subsequent heat treatment process, and then the open-circuit voltage of the solar cell is improved.

Embodiments of the present application will be described in detail below with reference to the accompanying drawings. However, as will be appreciated by those of ordinary skill in the art, in the various embodiments of the present application, numerous technical details have been set forth in order to provide a better understanding of the present application. However, the technical solutions claimed in the present application can be implemented without these technical details and with 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 view of a first cross-sectional structure of FIG. 1 along the line a1-a 2; FIG. 3 is a schematic view of a second cross-sectional structure taken along the line a1-a2 in FIG. 1; FIG. 4 is an enlarged view of a portion of FIG. 1 at A; fig. 5 is a schematic view of a first structure of a via portion in a solar cell according to an embodiment of the present disclosure; fig. 6 is a schematic view of a second structure of a via portion in a solar cell according to an embodiment of the present disclosure; fig. 7 is a schematic view of a second structure of a solar cell according to an embodiment of the present disclosure; fig. 8 is a schematic view of a third structure of a solar cell according to an embodiment of the present disclosure; FIG. 9 is a schematic diagram of a solar cell according to an embodiment of the present disclosure; fig. 10 is a schematic cross-sectional view of a solar cell according to an embodiment of the present disclosure; fig. 11 is a schematic diagram of a second cross-sectional structure of a solar cell according to an embodiment of the present disclosure.

It will be understood that the schematic cross-sectional structures in fig. 2, 3, 10 and 11 only illustrate the film layer on one side of the substrate, and the film layers on both sides of the substrate are not illustrated, and then the film layer on the other side of the substrate may be the same as or different from the film layer on one side of the substrate illustrated in the drawings, for example, the film layer on the other side of the substrate does not include a conductive layer, the functional film is located on the surface of the substrate, and each connection portion in the via portion is electrically connected to the surface of the substrate.

The area formed by the broken lines in fig. 1 to 11 is an area surrounded by at least three outermost via portions among one via portion of the electrode, and does not represent the actual area of the via portion or the via portion.

Referring to fig. 1-11, according to some embodiments of the present application, a solar cell is provided, the solar cell including a substrate 100.

The substrate 100 is a region that absorbs incident photons to generate photogenerated carriers. In some embodiments, the substrate 100 is a silicon substrate, which may include one or more of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. In some embodiments, the material of the substrate 100 may also be silicon carbide, an organic material, or a multi-compound. The multi-component compounds may include, but are not limited to, perovskite, gallium arsenide, cadmium telluride, copper indium selenium, and the like. Illustratively, the substrate 100 in the present embodiment is a monocrystalline silicon substrate.

In some embodiments, the substrate 100 has a doping element therein, where the doping element is of an N-type or a 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 internal doping element type is P-type. For another example, when the substrate 100 is an N-type substrate, the internal doping element type is N-type.

In some embodiments, the substrate 100 includes a first edge 11, the first edge 11 being edges on opposite sides along the first direction X. The substrate 100 includes a second edge 12, the second edge 12 being edges on opposite sides in a second direction Y. The first direction X and the second direction Y are parallel to the surface of the substrate 100, and the first direction X is perpendicular to the second direction Y.

In some embodiments, the substrate 100 includes a first central axis c1-c2, the first central axis c1-c2 being the central axis of the substrate 100 along the first direction X. The substrate 100 includes a second central axis b1-b2, and the second central axis b1-b2 is a central axis of the substrate 100 along the second direction Y.

The solar cell may include: a conductive layer 102. The conductive layer 102 is located on the substrate 100.

In some embodiments, the substrate 100 includes opposing first surfaces (e.g., light receiving surfaces) and second surfaces (e.g., backlight surfaces).

Referring to fig. 2, the conductive layer 102 may be located on a first surface of the substrate 100. The conductive layer 102 is an emitter of the solar cell, and the conductive layer 102 has a doping element type different from that of the substrate 100. For example, the substrate 100 is an N-type substrate, and the conductive layer 102 is doped with a P-type doping element. For another example, the substrate 100 is a P-type substrate, and the conductive layer 102 is doped with an N-type doping element.

In some embodiments, the conductive layer 102 may be formed based on the same original substrate as the substrate 100, and a portion of the original substrate is doped to form the conductive layer 102, and the remaining original substrate serves as the substrate 100.

In some embodiments, the surface of the conductive layer 102 may have a textured structure, so that the first surface of the substrate 100 has a smaller reflectivity for incident light and a larger absorption and utilization ratio for light.

In some embodiments, referring to fig. 3, the conductive layer 104 may be located on the second surface of the substrate 100 with the tunneling layer 101 between the substrate 100 and the conductive layer 104. The tunneling layer 101 and the conductive layer 104 may form a passivation contact structure of a cell, and the solar cell is a TOPCon (Tunnel Oxide Passivated Contact, tunneling oxide passivation contact) cell.

In some embodiments, the first surface and the second surface of the substrate 100 each have a conductive layer 104, and a tunneling layer is between at least one of the first surface or the second surface of the substrate 100 and the conductive layer 104, i.e., the solar cell may be a double-sided tunneling oxide passivation contact cell or a single-sided tunneling oxide passivation contact cell. For the double-sided tunneling oxide passivation contact battery, the first surface and the second surface are respectively provided with a tunneling layer and a conductive layer, and the electrodes corresponding to the tunneling oxide passivation contact battery are respectively positioned on the first surface and the second surface. For a single-sided tunnel oxide passivation contact cell, one of the first surface or the second surface has a tunnel layer and a conductive layer.

In some embodiments, the material of the tunneling layer 101 may include, but is not limited to, dielectric materials such as aluminum oxide, silicon nitride, silicon oxynitride, intrinsic amorphous silicon, and intrinsic polysilicon. The thickness of the tunneling layer 101 may be 0.5nm to 2.5nm, 0.5nm to 2nm, or 0.5nm to 1.2nm.

In some embodiments, the material of the conductive layer 104 may be at least one of a polycrystalline semiconductor, an amorphous semiconductor, or a microcrystalline semiconductor. The material of the conductive layer 104 includes at least one of polysilicon, amorphous silicon, or microcrystalline silicon.

In some embodiments, the thickness of the conductive layer 104 ranges from 40nm to 150nm or from 60nm to 90nm. The conductive layer 104 can ensure that optical loss due to absorption of the conductive layer 104 itself is small within any of the above thickness ranges. The thickness range of the conductive layer 104 can ensure that the passivation effect of the passivation contact structure formed by the conductive layer 104 and the tunneling layer 101 is better, which is beneficial to improving the battery efficiency. It will be appreciated that the conductive layer 104 shown in fig. 3 is not an identical element to the conductive layer 102 shown in fig. 2, for example, the conductive layer 104 shown in fig. 3 is doped polysilicon, and the doping element type in the doped polysilicon is the same as the doping element type of the substrate 100; the conductive layer 102 shown in fig. 2 is an emitter, and the doping element type in the emitter is different from the doping element type of the substrate 100.

In some embodiments, the solar cell includes a functional film 103, the functional film 103 being located on a surface of the conductive layer 102 (fig. 2), and/or a surface of the conductive layer 104 (fig. 3).

The functional film 103 may have a single-layer or laminated structure.

In some embodiments, the functional film 103 is a single layer structure. The material of the functional film 103 may be one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride oxide, titanium oxide, hafnium oxide, aluminum oxide, and the like. For example, the functional film 103 is a silicon nitride layer or a silicon oxynitride layer, and the functional film 103 serves as a passivation layer and an antireflection layer. The refractive index of the silicon nitride layer or the silicon oxynitride layer is higher, so that the reflection loss of the surface of the cell is reduced, and the open-circuit voltage of the solar cell is improved.

In some embodiments, the functional film 103 is a laminate structure. For example laminationA first passivation layer and a second passivation layer. The material of the first passivation layer is alumina, and the material of the second passivation layer can be any one or more of silicon oxide, silicon nitride or silicon oxynitride. When the first passivation layer is an alumina layer, the contact surface of the alumina layer and the substrate 100 has a relatively high fixed negative charge density Qf (Qf is about 10 ¹² ～10 ¹³ cm ^-2 ) An electric field having a negative polarity is formed on the surface of the substrate 100, and a good field effect passivation effect can be provided to the P-type surface by shielding minority carriers (minority carriers) and electrons of the same polarity on the P-type silicon surface. For example, a first passivation layer, a second passivation layer, and a third passivation layer. The material of the first passivation layer is silicon oxide, the material of the second passivation layer is aluminum oxide, and the material of the third passivation layer can be any one or more of silicon oxide, silicon nitride or silicon oxynitride. The first passivation layer is a silicon oxide layer, so that interface state defects of the contact surface between the silicon oxide and the substrate can be reduced, and contact resistance between the functional film 103 and the substrate 100 can be reduced.

In some embodiments, a solar cell includes: at least one electrode 110, each electrode 110 of the at least one electrode extending along a first direction X.

In some embodiments, the electrode 110 may be screen printed from a paste and then sintered. The material of the electrode 110 may be one or more of aluminum, silver, nickel, gold, molybdenum, or copper.

In some embodiments, the electrode 110 may be prepared by electroplating in a plurality of electroplating processes, the electrode 110 including a seed layer, a conductive layer, and a protective layer stacked.

In some embodiments, the electrode 110 is an upper electrode or a front electrode, and the electrode 110 is one of a positive electrode or a negative electrode. In some embodiments, electrode 110 is a bottom electrode or a back electrode. In some cases, the electrode 110 refers to a thin gate line or finger gate line to distinguish from a main gate line or bus bar.

In some embodiments, electrode 110 is in contact with conductive layer 102. The contact between the electrode 110 and the conductive layer 102 may be a localized contact or a full contact.

It is understood that 6 electrodes shown in fig. 1 are exemplary, and the number of electrodes is only 1 or more. In some embodiments, each electrode 110 includes: a main body 112, the main body 112 being located on a side of the functional film 103 away from the substrate 100 and extending in a first direction X; and a plurality of via portions 111 spaced apart along the first direction X, each of the plurality of via portions 111 penetrating through the functional film 103 and having one end in electrical contact with the body portion 112 and the other end electrically connected to the conductive layer 102.

In some embodiments, each via portion 111 includes a plurality of connection portions 107 penetrating the functional film 103, the plurality of connection portions 107 being discrete from one another. By arranging the discontinuous connection portions 107, the area of a single via hole portion 111 comprising a plurality of connection portions 107 is reduced, the area of a groove formed in the functional film 103 corresponding to the single via hole portion 111 is reduced, the damage area of the functional film 103 is reduced, the integrity of the functional film 103 is ensured to a certain extent, and the open-circuit voltage of the solar cell is improved. The connecting portions 107 which are distributed and discontinuous are arranged, the area of a local slotting region for accommodating the connecting portions 107 is reduced, damage to the film layers around the slotting region is reduced, the appearance integrity of the film layers of the slotting region is good, the solar cell is enabled to have the possibility of repairing in the subsequent heat treatment process, and then the open-circuit voltage of the solar cell is improved.

In some embodiments, the main body 112 and the conductive layer 102 are electrically connected through the connection portion 107, and photo-generated carriers generated in the substrate 100 are collected into the main body 112 by the connection portion 107, and then are collected into the collecting device by the solder strip.

In some embodiments, the orthographic projection shape of each via portion 111 of the plurality of via portions on the conductive layer 102 may be circular, rectangular, or any shape.

In some embodiments, the connection portion 107 has an irregular shape in front projection on the surface of the conductive layer 102. In this way, the interval between the irregular pattern and the front of the irregular pattern is smaller, so that the laser damage area of the single via hole 111 is relieved, the passivation area of the functional film 103 is increased, and the open-circuit voltage of the solar cell is improved.

In some embodiments, referring to fig. 4, in the second direction Y, the width d of the via portion 111 is less than or equal to the width w of the body portion 112 corresponding thereto. The electrical connection relationship between each connection portion 107 in the via portion 111 and the main body portion 112 can enable carriers formed in the substrate 100 to be collected into the electrode, and when the width d of the via portion 111 is smaller than or equal to the width w of the main body portion 112, the situation that the notch opened in the notch area is large, which causes waste of materials for forming the connection portion and the main body portion, can also reduce damage to the functional film 103, and is beneficial to improving the battery efficiency of the solar battery can be avoided.

In some embodiments, the width d of the via 111 ranges from 3 μm to 5 μm along the second direction Y. The width d of the via hole 111 is 3.6 μm to 5 μm, 3.3 μm to 4.6 μm, 3.1 μm to 4.2 μm, 4.2 μm to 5 μm, or 3.7 μm to 4.8 μm. The width d of the via portion 111 is within any range described above, so that the width of the body portion 112 is ensured to be moderate, and the shielding area of the electrode 110 is small, and each connection portion 107 in the via portion 11 may have a large area to form a bridge for communication between the electrode and the conductive layer 102, thereby reducing the series resistance of the electrode.

In some embodiments, referring to fig. 4, along the first direction X, the first spacing S is less than 4 times L, the first spacing S is a spacing between two adjacent via portions 111, and L is a length of the via portion 111 in the first direction X. In this way, the path of the via portion 111 for collecting the current is suitable, the path loss of the current is small, and the cell efficiency of the solar cell is high.

In some embodiments, the ratio Q of the first area to the second area satisfies 10% < Q < 100%, the first area is a total orthographic projection area of the bottoms of the plurality of connection portions 107 on the surface of the conductive layer 102, and the second area is an orthographic projection area of an area surrounded by at least three connection portions 107 on the outermost side in the via portion 111 on the surface of the conductive layer 102. The ratio Q satisfies 19% < Q < 89%, 25% < Q < 97%, 37% < Q < 94%, 53% < Q < 69%, 58% < Q < 86% or 24% < Q < 54%. The ratio Q of the first area to the second area satisfies the above arbitrary range, the contact area between the connection portion 107 and the conductive layer 102 is appropriate, the capability of collecting carriers by the electrode is better, and the laser damage in the via portion 111 is smaller, the damage to the functional film 103 is smaller, and the passivation efficiency of the functional film 103 is improved.

It can be understood that the area surrounded by the outermost at least three connection portions 107 may be the area fitted by the outermost at least three connection portions 107 in the via portion 111 as shown in fig. 5, or may be the area surrounded by the connecting lines between the opposite edges of the outermost at least three connection portions 107 in the via portion 111 as shown in fig. 6.

In some embodiments, the ratio of the third area to the first area is less than 38%, and the third area is an orthographic projection area of the bottom of each connection portion 107 of the plurality of connection portions on the surface of the conductive layer 102. The area of the single connecting portion 107 can ensure that more electrode materials are sufficiently contained in a single area of the connecting portion 107, namely, the contact area of the electrode 110 and the substrate 100 is sufficient, the better open-circuit voltage and the lower short-circuit current are achieved, and damage to the functional film 103 can be reduced by reducing the grooving area of the single connecting portion 107.

In some embodiments, the first ratio Q1 of one via portion 111 is different from the second ratio Q2 of another via portion 111. In this way, the ratio Q of the via hole 111 can be flexibly adjusted according to the position of the via hole 111 and the requirement of the solar cell, so as to balance the passivation performance of the functional film 103 and the electrical performance of the electrode 110, thereby obtaining a solar cell with higher cell efficiency.

Similarly, the order of arrangement of the plurality of connection portions 107 of any one via portion 111 is different from the order of arrangement of the plurality of connection portions 107 of another via portion 111. The embodiment of the application can flexibly set the morphology of the connecting part 107 and the arrangement sequence of the connecting parts 107, and reduces the process difficulty of preparing the via hole part 111 containing the connecting part 107.

In some embodiments, along the first direction X, the second area of the via portion 111 near the edge of the main portion 112 is smaller than the fourth area, where the fourth area is the orthographic projection area of the area surrounded by the at least three connection portions 107 on the outermost side of the via portion 111 corresponding to the middle position of the main portion 112 on the surface of the conductive layer 102. The source material of the main body 112 deposited on the via hole 111 with the smaller second area is correspondingly less, so that the problem of more deposition near the first edge 11 of the battery piece can be relieved, and a main body 112 with a relatively uniform width is obtained, and the shielding area of the electrode 110 formed by the main body 112 and the via hole 111 is correspondingly reduced, so that the optical loss of the solar battery is reduced, and the photoelectric conversion efficiency of the solar battery is improved. The edge of the main body 112 may be considered to be close to the first edge 11 of the substrate 100, and the middle position of the main body 112 is the first central axis c1-c2 of the substrate along the first direction X.

In some embodiments, in the second direction M, the total area of orthographic projections of the plurality of connection portions 107 in the via portion 111 on the conductive layer 102 decreases, and the total area of orthographic projections of the plurality of connection portions 107 in the via portion 111 closer to the first edge 11 on the conductive layer 102 decreases. Therefore, in the process of depositing the plating material by using the via portion 111 as the seed layer to form the body portion 112, the deposition amount deposited thereon is correspondingly reduced to offset the increase of the deposition amount near the edge of the substrate 100 in the plating process, so that the body portion 112 with a relatively uniform line width can be prepared. The area arrangement of the connecting portion 107 in the via portion 111 satisfies the requirements of the via portion 111 for collecting current and reduces the shielding area of the electrode 110 to the battery piece, and also reduces the area of the slotting region of the functional film 103, thereby improving the passivation effect of the functional film 103 and being beneficial to improving the open circuit voltage and the battery efficiency of the solar battery.

The second direction M is a direction in which the middle of the main body 112 points toward the end of the main body 112, i.e., a direction from the first central axis c1-c2 toward the first edge 11.

In some embodiments, referring to fig. 7, in the first direction X, the second pitch S2 is greater than the third pitch S1, the second pitch S2 is a pitch of two adjacent via portions 111 near the edge of the body portion 112, and the third pitch S1 is a pitch of any two adjacent via portions 111 except for two adjacent via portions 111 near the edge of the body portion 112. In this way, the second spacing S2 between the via portions 111 near the first edge 11 of the battery piece is larger, and the length of the functional film 103 to be covered by a certain amount of source material deposited in the fixing region where the main body portion 112 needs to be formed is correspondingly increased. In the case that the height of the main body 112 is unchanged, in the volume of the fixed main body 112, the length of the main body 112 in the first direction X is increased to reduce the width of the main body 112 in the third direction Y, so as to reduce the shielding area of the main body 112, further reduce the optical loss of the solar cell, and facilitate the improvement of the photoelectric conversion efficiency of the solar cell.

In some embodiments, referring to fig. 8, a solar cell includes: a plurality of electrodes 110 arranged at intervals along the second direction Y. The plurality of electrodes 110 are axisymmetric along the second central axis b1-b 2.

In some embodiments, referring to fig. 8, in the second direction Y, the first spacing k2 is greater than the second spacing r2, the first spacing k2 being the spacing between two via portions 111 corresponding to the electrodes 110 near the second edge 12 of the substrate 100 and near the first edge 11, and the second spacing r2 being the spacing between two via portions 111 corresponding to the electrodes 110 far from the second edge 12 of the substrate 100 and near the first edge 11. By setting the first interval k2 to be larger than the second interval r2, the amount of the plating material on the via portion 111 near the first edge 11 and the second edge 12 can be reduced, and the line width of the electrode 110 near the second edge 12 is substantially equal to the line width of the electrode 110 far from the second edge, so that the shielding area of the electrode is reduced. In some embodiments, the third interval k1 is greater than the fourth interval r1.

In some embodiments, referring to fig. 10, each electrode 110 further comprises: the extension portions 113, the extension portions 113 are located in the conductive layer 102, and each extension portion 113 is opposite to and contacts one of the connection portions 107 of the plurality of connection portions. The extension 113 increases the contact area between the electrode 110 and the conductive layer 102, reducing the series resistance of the electrode 110.

In some embodiments, referring to fig. 11, the body portion 112 may be a laminated structure including a first film layer 131, a second film layer 132, and a third film layer 133 on the surface of the functional film 103. The first film 131 and the connecting portion 111 are made of the same material and are all seed layers of an electroless plating process, such as a nickel plating seed layer. The second film 132 is a copper layer, which has high electrical conductivity and low cost, and has good thermal conductivity. The third film 133 is a protective layer, and the third film 133 is a silver layer.

In some embodiments, the body portion 112 may include a second film layer and a third film layer that are laminated without the first film layer.

Correspondingly, the embodiment of the present application further provides a method for preparing a solar cell, which is used for preparing the solar cell provided in the above embodiment, and the parts which are the same as those of the above embodiment are not described herein again.

Fig. 12 to 14 are schematic cross-sectional structures of solar cells corresponding to each step in a method for manufacturing a solar cell according to an embodiment of the present disclosure; fig. 15 is an electron microscope image of a conductive layer in a solar cell according to an embodiment of the present application. The cross-sectional views shown in fig. 12 to 14 show only the film layer on the substrate side, and the film layer on the other side of the substrate may be identical to the film layer on the substrate side or may be different from the film layer on the substrate side.

Referring to fig. 12, the method of manufacturing a solar cell includes: a substrate 100 is provided. The preparation method of the solar cell comprises the following steps: a conductive layer 102 is formed, the conductive layer 102 being located on the substrate 100. The preparation method of the solar cell comprises the following steps: an original film layer 105 is formed, and the original film layer 105 is located on the surface of the conductive layer 102.

In some embodiments, the original film 105 is a single layer or a stacked layer structure, and the material of the original film 105 may be one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbonitride, titanium oxide, hafnium oxide, or aluminum oxide.

In some embodiments, the original film layer 105 is a silicon nitride layer or a silicon oxynitride layer. In some embodiments, the original film layer 105 is a stacked structure, such as a stacked first passivation layer and second passivation layer.

In some embodiments, referring to fig. 12 and 13, a method of manufacturing a solar cell includes: the original film layer 105 is subjected to slotting treatment to form an open mold pattern 106, the open mold pattern 106 comprises a treatment part and a plurality of grooves 108, each groove 108 of the plurality of grooves 108 penetrates through the original film layer 105, the treatment part is located between every two grooves 108 of the plurality of grooves, and the remaining original film layer 105 and the treatment part serve as the functional film 103.

In some embodiments, a process model is disposed on the surface of the original film 105, where the process model corresponds to the open pattern 106. The partial region of the processing model is grooved to form grooves, and the original film layer 105 in the processing model which is not grooved is used as a processing part, and the processing part and the plurality of grooves 108 form an open pattern 106.

In some embodiments, when the ratio B of the fifth area to the sixth area satisfies 10% < B <100%, the fifth area is a total orthographic projection area of the bottoms of the plurality of grooves 108 on the surface of the conductive layer 102, and the sixth area is an orthographic projection area of the open pattern 106 on the surface of the conductive layer 102. For example, at a ratio B of 30%, the process parameters of the laser treatment include: the laser power was 13.3%, the laser speed was 5m/s and the laser frequency was 1000KHZ. For another example, when the ratio B is 65%, the process parameters of the laser treatment include: the laser power was 14.2%, the laser speed was 5m/s and the laser frequency was 1000KHZ. For another example, when the ratio B is 93%, the process parameters of the laser treatment include: the laser power was 15.1%, the laser speed was 5m/s and the laser frequency was 1000KHZ.

The ratio P of the fifth area to the sixth area is changed by adjusting and controlling the laser parameters, so that the contact area between the connecting portion formed in the groove 108 and the conductive layer 102 is proper, the capability of collecting carriers by the electrode is good, the laser damage in the via hole is small, the damage to the functional film 103 is small, and the passivation effect of the functional film 103 is improved.

Referring to fig. 14 and 15, during the formation of the recess 108, a portion of the thickness of the conductive layer 102 may be etched, thereby forming a recess 109 in the conductive layer 102.

In some embodiments, a method of manufacturing a solar cell includes: and (3) performing hydrofluoric acid etching treatment to remove an oxide layer generated on the surface of the functional film 103 when the groove 108 is formed, wherein the concentration of hydrofluoric acid is 0.1-50%, and the etching time of the etching treatment is 1-600 s.

Referring to fig. 13 and 2, the method of manufacturing a solar cell includes: the conductive material fills the plurality of grooves 108 and is positioned on the part of the functional film 103, the conductive material positioned in each groove 108 of the plurality of grooves serves as a connecting part 107, the conductive material positioned on the part of the functional film 103 serves as a main body part 112, the main body part 112 extends along the first direction X, the plurality of connecting parts 107 form a via hole part 111, and the via hole part 111 is contacted with the main body part 112; the plurality of connection portions 111 and the main body portion 112 together constitute the electrode 110.

The conductive material located at the recess 109 is an extension portion, and the material of the extension portion is the same as that of the connection portion 107, and is formed in the same manufacturing process.

In some embodiments, the connection 107 is a nickel plated seed layer. The chemical plating method is adopted to carry out the nickel plating seed layer, the chemical nickel plating solution adopts low-phosphorus chemical nickel plating solution, the temperature of the chemical nickel plating solution is 80-95 ℃, and the time of the chemical nickel plating solution is 10-50min.

In some embodiments, the body portion 112 includes a stack of copper and silver layers. The process step of forming the copper layer includes the steps of placing the substrate 100 having the nickel plating seed layer in a copper tank to perform electroplating of the copper layer, plating the copper layer by a plating process, wherein the plating temperature is in the range of 25-55 ℃, the plating time is 5-50min, and the plating current density is 1-60ASD.

The process steps for forming the silver layer comprise: after the battery piece plated with the copper layer is cleaned, silver plating pretreatment and silver plating treatment are adopted, the reaction temperature is normal temperature, the silver plating pretreatment time is 30-300S, and the silver plating time is 1-10min.

In some embodiments, a method of manufacturing a solar cell includes: and (3) the electroplated battery piece is used for FGA annealing treatment, wherein the annealing temperature is 150-550 ℃, and the annealing time is 3-300min.

Accordingly, the embodiment of the application also provides a photovoltaic module, the photovoltaic module includes: a cell string formed by connecting a plurality of solar cells 20 as described in any one of the above embodiments, or a solar cell 20 prepared by a method of preparing a plurality of solar cells as provided in the above embodiments; a packaging layer 21 for covering the surface of the battery string; a cover plate 22 for covering the surface of the encapsulation layer 21 facing away from the battery string.

In some embodiments, the packaging layer 21 may be an organic packaging adhesive film such as EVA or POE, and the packaging layer 21 covers the surface of the battery string to seal and protect the battery string. The encapsulation layer 21 includes an upper encapsulation film and a lower encapsulation film respectively covering both sides of the surface of the battery string.

The cover plate 22 may be a glass cover plate or a plastic cover plate, etc. for protecting the battery strings, and the cover plate 22 covers the surface of the encapsulation layer 21 facing away from the battery strings. In some embodiments, light trapping structures are provided on the cover plate 22 to increase the utilization of the 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 22 includes an upper cover 221 and a lower cover 222 on both sides of the battery string.

It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples of implementing 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. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention shall be defined by the appended claims.

Claims

1. A solar cell, comprising:

a substrate;

a conductive layer on the substrate;

the functional film is positioned on the surface of the conductive layer;

at least one electrode, each of the at least one electrode extending in a first direction; wherein each of the electrodes comprises:

a main body portion located at a side of the functional film away from the substrate and extending in the first direction;

a plurality of via portions spaced apart along the first direction, each of the plurality of via portions penetrating through the functional film and having one end in electrical contact with the main body portion and the other end in electrical connection with the conductive layer; wherein each of the via portions includes a plurality of connection portions penetrating the functional film, the plurality of connection portions being dispersed and discontinuous with each other.

2. The solar cell according to claim 1, wherein a ratio Q of a first area to a second area satisfies 10% < Q < 100%, the first area being a total orthographic projected area of bottoms of the plurality of connection portions on the surface of the conductive layer, and the second area being an orthographic projected area of an area surrounded by at least three connection portions outermost in the via portion on the surface of the conductive layer.

3. The solar cell of claim 2, wherein a ratio of a third area to the first area is less than 38%, the third area being an orthographic projected area of a bottom of each of the plurality of connection portions on the surface of the conductive layer.

4. The solar cell according to claim 2, wherein a first ratio Q1 of one of the via portions is different from a second ratio Q2 of the other via portion.

5. The solar cell according to claim 2 or 4, wherein, along the first direction, a second area of the via portion near the edge of the main body portion is smaller than a fourth area, and the fourth area is a front projection area of an area surrounded by at least three connection portions on the outermost side of the via portion corresponding to the middle position of the main body portion on the surface of the conductive layer.

6. The solar cell according to claim 1, wherein a width of the via portion is smaller than or equal to a width of the body portion corresponding thereto in the second direction; wherein the second direction is perpendicular to the first direction.

7. The solar cell according to claim 1 or 6, wherein the width of the via is in the range of 3 μm to 5 μm in the second direction.

8. The solar cell according to claim 1, wherein a first pitch is smaller than 4 times L in the first direction, the first pitch being a pitch of two adjacent via portions, L being a length of the via portions in the first direction.

9. The solar cell according to claim 8, wherein in the first direction, a second pitch is larger than a third pitch, the second pitch being a pitch of two adjacent via portions near the body portion edge and adjacent, and the third pitch being a pitch of any adjacent two via portions other than the two adjacent via portions near the body portion edge.

10. The solar cell according to claim 1, wherein an arrangement order of the plurality of connection portions of any one of the via portions is different from an arrangement order of the plurality of connection portions of another one of the via portions.

11. The solar cell according to claim 1, wherein the orthographic projection shape of the connection portion on the surface of the conductive layer is an irregular pattern.

12. The solar cell of claim 1, wherein each of the electrodes further comprises: and the extending parts are positioned in the conductive layer, and each extending part is opposite to and in contact with one connecting part of the plurality of connecting parts.

13. A method of manufacturing a solar cell, comprising:

providing a substrate;

forming a conductive layer on the substrate,

forming an original film layer, wherein the original film layer is positioned on the surface of the conductive layer;

grooving the original film layer to form a mold opening pattern, wherein the mold opening pattern comprises a processing part and a plurality of grooves, each groove of the plurality of grooves penetrates through the original film layer, the processing part is positioned between every two grooves of the plurality of grooves, and the rest of the original film layer and the processing part are used as functional films;

the conductive material fills the plurality of grooves and is positioned on part of the functional film, the conductive material positioned in each groove of the plurality of grooves is used as a connecting part, the conductive material positioned on part of the functional film is used as a main body part, the main body part extends along a first direction, a plurality of connecting parts form a via hole part, and the via hole part is contacted with the main body part; the plurality of connection portions and the main body portion together constitute an electrode.

14. The method of claim 13, wherein the grooving process comprises laser processing, etching slurry, or ion etching.

15. The method of manufacturing a solar cell according to claim 13, wherein forming the open pattern comprises:

and arranging a processing model on the surface of the original film layer, wherein the processing model corresponds to the die opening pattern, grooving the partial area of the processing model to form grooves, taking the original film layer in the processing model which is not subjected to grooving as a processing part, and forming the die opening pattern by the processing part and the grooves.

16. The method of claim 15, wherein the grooving process is a laser process, and the process parameters of the laser process include: the laser power is 12% -16%; the laser frequency is 800 KHZ-12000 KHZ.

17. A photovoltaic module, comprising:

a cell string formed by connection of a plurality of solar cells according to any one of claims 1 to 12 or a solar cell prepared by a method for preparing a plurality of solar cells according to any one of claims 13 to 16;

The packaging layer is used for covering the surface of the battery string;

and the cover plate is used for covering the surface of the packaging layer, which is away from the battery strings.