CN116404051A

CN116404051A - Back contact solar cell, manufacturing method thereof and photovoltaic module

Info

Publication number: CN116404051A
Application number: CN202310453244.4A
Authority: CN
Inventors: 周生厚; 唐喜颜; 杨建超; 邓小玉; 孙召清; 唐清; 王永磊; 叶枫; 方亮; 徐希翔
Original assignee: Longi Green Energy Technology Co Ltd
Current assignee: Longi Green Energy Technology Co Ltd
Priority date: 2023-04-24
Filing date: 2023-04-24
Publication date: 2023-07-07

Abstract

The invention discloses a back contact solar cell, a manufacturing method thereof and a photovoltaic module, and relates to the technical field of photovoltaics, so that damage to the back contact solar cell caused by laser energy is reduced or eliminated when an N region and a P region included in the back contact solar cell are isolated by a laser etching process. The back contact solar cell includes: a semiconductor substrate, a transparent conductive layer and an insulating light absorbing layer. The semiconductor substrate has opposite first and second sides. The second face has N-type regions and P-type regions alternately spaced apart, and isolation regions between each N-type region and the corresponding P-type region. The transparent conductive layer covers the second surface. And each isolation region is provided with an isolation groove penetrating through the transparent conductive layer, and the isolation groove is used for isolating the part of the transparent conductive layer on the N-type region from the part of the transparent conductive layer on the P-type region. The insulating light absorption layer is at least positioned at the bottom of the isolation groove, and the width of the insulating light absorption layer is larger than or equal to the width of the isolation groove.

Description

Back contact solar cell, manufacturing method thereof and photovoltaic module

Technical Field

The invention relates to the technical field of photovoltaics, in particular to a back contact solar cell, a manufacturing method thereof and a photovoltaic module.

Background

The back contact solar cell refers to a solar cell with an emitter and a metal contact both on the back of the cell and the front of the cell is not shielded by a metal electrode. Compared with a solar cell with a shielding front surface, the back contact solar cell has higher short-circuit current and photoelectric conversion efficiency, and is one of the technical directions for realizing the high-efficiency crystalline silicon cell at present.

However, in the conventional manufacturing method, the process for isolating the N region and the P region included in the back contact solar cell is liable to damage the back contact solar cell, resulting in a decrease in yield of the back contact solar cell, which is disadvantageous for improving electrical performance of the back contact solar cell.

Disclosure of Invention

The invention aims to provide a back contact solar cell, a manufacturing method thereof and a photovoltaic module, so that damage to the back contact solar cell caused by laser energy is reduced or eliminated under the condition that the N region and the P region included in the back contact solar cell are isolated by adopting a laser etching process, the yield of the back contact solar cell is improved, and the electrical property of the back contact solar cell is improved.

In a first aspect, the present invention provides a back contact solar cell comprising: a semiconductor substrate, a transparent conductive layer and an insulating light absorbing layer.

The semiconductor substrate has opposite first and second sides. The second face has N-type regions and P-type regions alternately spaced apart, and isolation regions between each N-type region and the corresponding P-type region. The transparent conductive layer covers the second surface. And each isolation region is provided with an isolation groove penetrating through the transparent conductive layer, and the isolation groove is used for isolating the part of the transparent conductive layer on the N-type region from the part of the transparent conductive layer on the P-type region. The insulating light absorption layer is at least positioned at the bottom of the isolation groove, and the width of the insulating light absorption layer is larger than or equal to the width of the isolation groove.

Under the condition of adopting the technical scheme, in the back contact solar cell provided by the invention, the second surface of the semiconductor substrate is provided with N-type regions and P-type regions which are alternately distributed, and isolation regions positioned between each N-type region and the corresponding P-type region. The isolation region can isolate the N-type region and the P-type region with opposite conductivity types, so that the recombination of carriers at the transverse junction of the N-type region and the P-type region is inhibited, and the photoelectric conversion efficiency of the back contact solar cell is improved. In addition, the back contact solar cell includes a transparent conductive layer overlying the second face. The part of the transparent conductive layer positioned on the N-type region can reduce the contact potential barrier between the N-type region and the first electrode, and is beneficial to the export of electrons. The part of the transparent conductive layer positioned on the P-type region can reduce the contact potential barrier between the P-type region and the second electrode, and is beneficial to leading out holes. Based on the above, an isolation groove penetrating through the transparent conductive layer is formed on each isolation region, and the isolation groove is used for isolating the part of the transparent conductive layer on the N-type region from the part of the transparent conductive layer on the P-type region, so that the back contact solar cell is prevented from being shorted, and the electrical stability of the back contact solar cell is improved.

Second, the back contact solar cell further comprises an insulating light absorbing layer at least at the bottom of the isolation trench. Because the insulating light absorption layer is a non-conductive film layer, the part of the transparent conductive layer positioned on the N-type region and the part of the transparent conductive layer positioned on the P-type region cannot be conducted through the insulating light absorption layer, and the back contact solar cell can be prevented from being short-circuited. Meanwhile, the insulating light absorption layer also has light absorption characteristics. In this case, after the transparent conductive layer is formed to cover the second surface, even if the isolation grooves penetrating through the transparent conductive layer are formed on each isolation region by using a laser etching process, the existence of the insulating light absorption layer can reduce or even eliminate the damage of the laser to the film layer below the transparent conductive layer while ensuring that the transparent conductive layer is completely etched through, so that the yield of the back contact solar cell is improved. Meanwhile, the problems that the manufacturing cost is high and large-scale mass production is not suitable due to the fact that the isolation groove is formed in the prior art in a mode of combining photoetching with wet etching or in a mode of combining ink printing with wet etching can be solved, the manufacturing cost of the back contact solar cell is reduced, and the mass production of the back contact solar cell is improved.

As a possible implementation, the width of the insulating light absorbing layer is greater than the width of the isolation trench. The insulating light absorption layer is also positioned between a part of the transparent conductive layer and a part of the semiconductor substrate corresponding to the isolation region.

Under the condition of adopting the technical scheme, in the actual manufacturing process, the width of the isolation groove is the etching width of the transparent conductive layer by the laser etching process. Based on the above, when the width of the insulating light absorption layer is larger than the width of the isolation groove, the width of the insulating light absorption layer is also larger than the etching width of the transparent conductive layer by the laser etching process. And the insulating light absorption layer is also positioned on a part of the transparent conductive layer and a part of the semiconductor substrate corresponding to the isolation region. At this time, the existence of the insulating light absorption layer can ensure that the damage of the bottom of the isolation groove corresponding to the semiconductor substrate and the part near the corresponding isolation groove caused by laser etching can be reduced or eliminated, and the yield of the back contact solar cell is further improved.

As a possible implementation, the thickness of the two side edge regions of the insulating light-absorbing layer is gradually reduced along the width direction of the isolation groove.

Under the condition of adopting the technical scheme, when the isolation groove penetrating through the whole transparent conductive layer covered on the second surface is formed by adopting the laser etching process in the actual manufacturing process, the etching strength of the laser on the part of the transparent conductive layer corresponding to the middle part of the isolation groove is larger. On this account, in the case where the thickness of both side edge regions of the insulating light-absorbing layer gradually decreases in the width direction of the isolation groove, it is explained that the thickness of the insulating light-absorbing material for manufacturing the insulating light-absorbing layer is large in the center region in the width direction. Accordingly, the insulating light absorption material has strong light absorption characteristics along the central area of the width direction, so that damage to the film layer of the semiconductor substrate at the bottom of the isolation groove caused by laser can be further reduced or even eliminated. In addition, along the width direction of the isolation groove, the thickness of the two side edge areas of the insulating light absorption layer is gradually reduced, the consumption of consumable materials in the two side edge areas of the insulating light absorption layer can be reduced, and the manufacturing cost of the insulating light absorption layer is reduced. Meanwhile, the surface of one side of the insulating light absorption material, which is away from the transparent conductive layer, is convex, so that the light absorption area of one side of the insulating light absorption material, which is away from the transparent conductive layer, can be increased, the unit light absorption amount of one side of the insulating light absorption material, which is away from the transparent conductive layer, can be reduced, the damage degree of a laser etching process to the insulating light absorption material for manufacturing the insulating light absorption layer can be reduced, the manufacturing thickness of the insulating light absorption material can be reduced, and the consumption of consumables of the insulating light absorption material can be further reduced.

As a possible implementation manner, a side of the insulating light absorbing layer, which is in contact with the transparent conductive layer, has at least one light trapping structure.

Under the condition of adopting the technical scheme, the light trapping structure can be used for forming the isolation groove penetrating through the transparent conductive layer by adopting a laser etching process, so that more laser can be projected into the insulating light absorbing material for manufacturing the insulating light absorbing layer, the influence on the appearance of the side wall part of the isolation groove corresponding to the transparent conductive layer caused by laser scattering is prevented, the appearance of the two side walls of the transparent conductive layer along the width direction of the isolation groove is ensured to meet the working requirement, and further, all partial areas of the transparent conductive layer along the width direction of the isolation groove are ensured to have good conductive characteristics, so that the photoelectric conversion efficiency of the back contact solar cell is improved.

As a possible implementation manner, the light trapping structure is a concave structure recessed into the insulating light absorbing layer. In this case, in the actual manufacturing process, only screen printing, ink jet or other modes can be adopted, so that the insulating light absorbing material with the light trapping structure, the shape of which meets the working requirements, can be formed on the isolation region, no additional processing procedure is required for forming the light trapping structure, the manufacturing process of the insulating light absorbing material for manufacturing the insulating light absorbing layer is simplified, and the manufacturing difficulty of the insulating light absorbing material is reduced.

As a possible implementation manner, the concave structure is a hemispherical concave structure.

Under the condition of adopting the technical scheme, the hemispherical concave structure is regular in shape, the manufacturing process precision is not strictly required for forming the light trapping structure with a complex shape, and the manufacturing difficulty of the insulating light absorbing material is further reduced. In addition, the hemispherical concave structure is a concave structure with high symmetry, and the surface morphology of each partial area of the surface of the concave structure is the same, so that each partial area of the insulating light absorption material has excellent light trapping effect, and the side wall morphology of the transparent conductive layer along the width direction is further ensured to meet the working requirement.

As one possible implementation, the width of the insulating light absorbing layer is 5 μm or more and 5mm or less.

Under the condition of adopting the technical scheme, as described above, the width of the insulating light absorption layer is greater than or equal to the width of the isolation groove. In this case, the width of the insulating light absorbing layer is within the above range, and thus, it is possible to prevent the portion of the transparent conductive layer located on the N-type region from being difficult to separate from the portion of the transparent conductive layer located on the P-type region due to the smaller width of the insulating light absorbing layer, which makes the width of the isolation groove smaller, and suppress leakage. Meanwhile, the large consumption of the insulating light absorption layer caused by the large width of the insulating light absorption layer can be prevented, and the manufacturing cost of the insulating light absorption material for manufacturing the insulating light absorption layer is reduced. In addition, the area of the transparent conductive layer covered on the N-type region and the P-type region is reduced due to the fact that the width of the isolation groove is larger because of the larger width of the insulating light absorption layer can be prevented, and carriers generated by the semiconductor substrate in a working state cannot be timely led out by the transparent conductive layer, so that the photoelectric conversion efficiency of the back contact solar cell can be improved due to the width of the insulating light absorption layer in the range.

As a possible implementation manner, the material of the insulating light absorbing layer is ink, photoresist or UV-curable glue.

Under the condition of adopting the technical scheme, the printing ink, the photoresist and the UV curing adhesive all have good light absorption characteristics, so that under the condition that the material of the insulating light absorption layer is one of the materials, the damage to the part of the semiconductor substrate corresponding to the isolation region caused by laser can be reduced or even eliminated by manufacturing the insulating light absorption material of the insulating light absorption layer in the process of forming the isolation groove by adopting the laser etching process.

As one possible implementation manner, the conductor substrate includes: a semiconductor substrate, a first semiconductor stack, and a second semiconductor stack. The first semiconductor stack is formed at least on a portion of the semiconductor substrate corresponding to the N-type region. The first semiconductor stack includes a first passivation layer, and an N-doped semiconductor layer located on the first passivation layer in a direction away from the semiconductor substrate. The second semiconductor stack is formed at least on a portion of the semiconductor substrate corresponding to the P-type region. The second semiconductor stack includes a second passivation layer, and a P-type doped semiconductor layer on the second passivation layer in a direction away from the semiconductor substrate.

With the adoption of the technical scheme, the first semiconductor lamination and the second semiconductor lamination are both selective contact structures. Based on the above, the selective contact structure has excellent interface passivation effect and selective collection of carriers, so the first semiconductor lamination and the second semiconductor lamination which are both selective contact structures can further improve the photoelectric conversion efficiency of the back contact solar cell. In addition, the chemical properties of the first passivation layer and the second passivation layer are easily changed in a high temperature scene. For example: when at least one of the first passivation layer and the second passivation layer is an intrinsic amorphous silicon layer, in the case of forming the isolation trench using a laser etching process, the high temperature laser may cause the intrinsic amorphous silicon layer to be formed on the isolation region or a portion located near the isolation region to easily form polycrystalline silicon or monocrystalline silicon, thereby affecting the interface passivation effect of the portion and the selective collection of carriers. Based on the above, the existence of the insulating light absorption layer can reduce or even eliminate the damage of the laser to the first passivation layer and/or the second passivation layer, so that the back contact solar cell has excellent working performance.

As a possible implementation manner, the first semiconductor stack is further formed on a portion of the semiconductor substrate corresponding to the isolation region, and the second semiconductor stack is further formed above a portion of the first semiconductor stack corresponding to the isolation region; or, the second semiconductor stack is further formed on a portion of the semiconductor substrate corresponding to the isolation region, and the first semiconductor stack is further formed over a portion of the second semiconductor stack corresponding to the isolation region. In this case, the semiconductor substrate further includes an insulating layer between a portion of the first semiconductor stack corresponding to the isolation region and a portion of the second semiconductor stack corresponding to the isolation region.

Under the condition of adopting the technical scheme, carriers of corresponding conductivity types can respectively pass through the first passivation layer and the second passivation layer through tunneling effect and are collected by the N-type doped semiconductor layer or the P-type doped semiconductor layer. Based on this, when the portion of one of the first semiconductor stack and the second semiconductor stack corresponding to the isolation region is located on the portion of the other corresponding to the isolation region, the insulating layer can isolate the portion of the first semiconductor stack corresponding to the isolation region from the portion of the second semiconductor stack corresponding to the isolation region, so that recombination of carriers at the longitudinal boundary of the first semiconductor stack and the second semiconductor stack is prevented, and the photoelectric conversion efficiency of the back contact solar cell is further improved.

In a second aspect, the present invention further provides a photovoltaic module, which includes the back contact solar cell provided in the first aspect and various implementations thereof.

The beneficial effects of the second aspect of the present invention may refer to the beneficial effect analysis in the first aspect and various implementation manners thereof, which are not described herein.

In a third aspect, the present invention also provides a method for manufacturing a back contact solar cell, the method comprising: first, a semiconductor substrate is formed. The semiconductor substrate has opposite first and second sides. The second face has N-type regions and P-type regions alternately spaced apart, and isolation regions between each N-type region and the corresponding P-type region. Next, an insulating light absorbing material is formed over at least a portion of the isolation region. Then, a transparent conductive layer is formed to cover the N-type region, the P-type region and the insulating light absorbing material. Then, a laser etching process is used to form isolation trenches penetrating through the transparent conductive layer on each isolation region, and the remaining insulating light absorbing material is made to form an insulating light absorbing layer. The isolation groove is used for isolating the part of the transparent conductive layer located on the N-type region from the part of the transparent conductive layer located on the P-type region. The insulating light absorption layer is at least positioned at the bottom of the isolation groove, and the width of the insulating light absorption layer is greater than or equal to the width of the isolation groove.

As a possible implementation manner, the top surface area of the portion of the insulating light absorbing material corresponding to the isolation groove is larger than the bottom surface area of the portion of the insulating light absorbing material corresponding to the isolation groove.

As a possible implementation, the average thickness of the middle region of the insulating light-absorbing material is greater than the average thickness of the two side edge regions of the insulating light-absorbing material in the width direction of the isolation groove.

As a possible implementation manner, a plurality of light trapping structures are arranged on the side of the insulating light absorbing material facing away from the semiconductor substrate.

As a possible implementation, the plurality of light trapping structures are uniformly distributed on a side of the insulating light absorbing material facing away from the semiconductor substrate. In this case, the light trapping effect of each part of the insulating light absorbing material is approximately the same, so that the area of the semiconductor substrate covered by each part of the insulating light absorbing material can be effectively protected, and the yield of the back contact solar cell is further improved.

As one possible implementation, the insulating light absorbing material is formed using a screen printing process or an inkjet printing process.

With the above technical solution, the screen printing process and the inkjet printing process are conventional processes for manufacturing back contact solar cells. Based on this, the insulating light absorbing material may be formed using a screen printing process or an inkjet printing process without using a separately manufactured apparatus for forming the insulating light absorbing material. In other words, the manufacturing method of the back contact solar cell provided by the invention can be compatible with the conventional manufacturing process and equipment of the conventional back contact solar cell, reduce the manufacturing difficulty of the back contact solar cell and improve the manufacturing efficiency.

As one possible implementation manner, the minimum thickness of the portion of the insulating light absorbing material corresponding to the isolation groove is greater than or equal to 0.05 μm and less than or equal to 100 μm.

Under the condition of adopting the technical scheme, the minimum thickness of the part of the insulating light absorption material corresponding to the isolation groove is in the range, so that the part of the insulating light absorption material corresponding to the isolation groove can be prevented from being completely etched by laser before the part of the insulating light absorption material corresponding to the isolation groove is incompletely etched through the transparent conducting layer, the part of the insulating light absorption material corresponding to the isolation area of the semiconductor substrate can be protected in the whole etching process, and the high yield of the back contact solar cell can be further ensured. Meanwhile, the consumption of the insulating light absorbing material is prevented from being large due to the fact that the minimum thickness is large, and the manufacturing cost of the insulating light absorbing material is reduced.

As one possible implementation manner, the forming a semiconductor substrate includes: a semiconductor substrate is provided. Next, a first semiconductor stack is formed on at least a portion of the semiconductor substrate corresponding to the N-type region. The first semiconductor stack includes a first passivation layer, and an N-doped semiconductor layer located on the first passivation layer in a direction away from the semiconductor substrate. A second semiconductor stack is formed over at least a portion of the semiconductor substrate corresponding to the P-type region. The second semiconductor stack includes a second passivation layer, and a P-type doped semiconductor layer on the second passivation layer in a direction away from the semiconductor substrate. The semiconductor base includes a semiconductor substrate, a first semiconductor stack, and a second semiconductor stack.

As a possible implementation manner, the first semiconductor stack is further formed on a portion of the semiconductor substrate corresponding to the isolation region, and the second semiconductor stack is further formed above a portion of the first semiconductor stack corresponding to the isolation region; or, the second semiconductor stack is further formed on a portion of the semiconductor substrate corresponding to the isolation region, and the first semiconductor stack is further formed over a portion of the second semiconductor stack corresponding to the isolation region. In the above case, the method for manufacturing the back contact solar cell further includes: an insulating layer is formed between a portion of the first semiconductor stack corresponding to the isolation region and a portion of the second semiconductor stack corresponding to the isolation region.

The advantages of the third aspect and various implementations of the present invention may be referred to for analysis of the advantages of the first aspect and various implementations of the first aspect, which are not described here in detail.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:

Fig. 1 is a schematic longitudinal cross-sectional view of a back contact solar cell according to an embodiment of the present invention;

FIG. 2 is an enlarged schematic view of a structure at a separation tank according to an embodiment of the present invention;

FIG. 3 is an enlarged schematic view of another structure at a separation tank according to an embodiment of the present invention;

FIG. 4 is an enlarged schematic view of another embodiment of the present invention showing the isolation slot;

fig. 5 is a schematic view of a longitudinal cross section of a back contact solar cell according to an embodiment of the present invention;

fig. 6 is a schematic diagram showing a longitudinal cross section of a back contact solar cell in the manufacturing process according to the second embodiment of the present invention;

fig. 7 is a schematic diagram of a longitudinal cross-section of a back contact solar cell in the manufacturing process according to an embodiment of the present invention;

fig. 8 is a schematic diagram showing a longitudinal cross section of a back contact solar cell in the manufacturing process according to an embodiment of the present invention;

fig. 9 is a schematic diagram showing a longitudinal cross section of a back contact solar cell in the manufacturing process according to an embodiment of the present invention;

fig. 10 is a schematic longitudinal cross-sectional view of a back contact solar cell according to an embodiment of the present invention in a manufacturing process;

fig. 11 is a schematic diagram seventh of a longitudinal cross-section of a back contact solar cell in the manufacturing process according to an embodiment of the present invention;

FIG. 12 is a schematic longitudinal cross-sectional view of a structure after forming an insulating light absorbing material in accordance with an embodiment of the present invention;

FIG. 13 is a schematic longitudinal cross-sectional view of another embodiment of the present invention after forming an insulating light absorbing material;

FIG. 14 is a schematic longitudinal cross-sectional view of yet another embodiment of the present invention after forming an insulating light absorbing material;

fig. 15 is a schematic view eighth in longitudinal cross-section of a back contact solar cell according to an embodiment of the present invention;

FIG. 16 is a schematic view of a longitudinal cross-section of a structure after forming transparent conductive material in accordance with an embodiment of the present invention;

FIG. 17 is a schematic view of a longitudinal cross-section of another structure after forming transparent conductive material in accordance with an embodiment of the present invention;

FIG. 18 is a schematic longitudinal cross-sectional view of still another embodiment of the present invention after forming transparent conductive material;

fig. 19 is a schematic longitudinal cross-sectional view of a back contact solar cell according to an embodiment of the present invention during the manufacturing process;

fig. 20 is a schematic longitudinal cross-sectional view of a back contact solar cell according to an embodiment of the present invention during a manufacturing process.

Reference numerals: 1 is a semiconductor substrate, 2 is a first passivation material layer, 3 is an N-type doped semiconductor material layer, 4 is an insulating material layer, 5 is a mask layer, 6 is a first passivation layer, 7 is an N-type doped semiconductor layer, 8 is a second passivation material layer, 9 is a P-type doped semiconductor material layer, 10 is a passivation anti-reflection layer, 11 is a second passivation layer, 12 is a P-type doped semiconductor layer, 13 is an insulating layer, 14 is an insulating light absorbing material, 15 is a transparent conductive layer, 16 is an isolation groove, 17 is an insulating light absorbing layer, 18 is a first electrode, and 19 is a second electrode.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is only exemplary and is not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure.

Various structural schematic diagrams according to embodiments of the present disclosure are shown in the drawings. The figures are not drawn to scale, wherein certain details are exaggerated for clarity of presentation and may have been omitted. The shapes of the various regions, layers and relative sizes, positional relationships between them shown in the drawings are merely exemplary, may in practice deviate due to manufacturing tolerances or technical limitations, and one skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions as actually required.

In the context of the present disclosure, when a layer/element is referred to as being "on" another layer/element, it can be directly on the other layer/element or intervening layers/elements may be present therebetween. In addition, if one layer/element is located "on" another layer/element in one orientation, that layer/element may be located "under" the other layer/element when the orientation is turned. In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise. The meaning of "a number" is one or more than one unless specifically defined otherwise.

In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

Currently, solar cells are increasingly used as new energy alternatives. Among them, a photovoltaic solar cell is a device that converts solar light energy into electric energy. Specifically, the solar cell generates carriers by utilizing the photovoltaic principle, and then the carriers are led out by using the electrodes, so that the electric energy can be effectively utilized.

When the positive electrode and the negative electrode of the solar cell are positioned on the back surface of the solar cell, the solar cell is a back contact solar cell. Existing back contact solar cells include metal wrap through (metal wrap through, abbreviated MWT) cells, interdigitated back contact (Interdigitated back contact, abbreviated IBC) cells, and the like. The IBC battery has the greatest characteristics that the emitter and the metal contact are positioned on the back surface of the battery, and the front surface is free from the influence of shielding of the metal electrode, so that the IBC battery has higher short-circuit current Isc. Meanwhile, the back side of the IBC cell may allow a wider metal gate line to reduce the series resistance Rs, so that the fill factor FF may be increased. In addition, the battery with the front surface free of shielding is high in conversion efficiency and attractive in appearance. Meanwhile, the assembly of the all back electrode is easier to assemble, so that the IBC battery is one of the technical directions for realizing the efficient crystalline silicon battery at present.

In practical applications, back contact solar cells typically include a semiconductor substrate and a transparent conductive layer. The semiconductor substrate has a first surface and a second surface opposite to each other. The second face has N-type and P-type regions alternately spaced apart along a direction parallel to the second face, and isolation regions between each of the N-type and P-type regions. The transparent conductive layer covers the second surface. And, each isolation region is formed with an isolation groove penetrating at least the transparent conductive layer, the isolation groove being used for isolating a portion of the transparent conductive layer located on the N-type region from a portion of the transparent conductive layer located on the P-type region. In this regard, in an actual manufacturing process, after the semiconductor substrate is formed, a physical vapor deposition process or the like is generally used to form the transparent conductive material covering the second surface. And then, patterning the part of the transparent conductive material on the isolation region to at least completely remove the part of the transparent conductive material corresponding to the space of the isolation groove, so as to isolate the N-type region from the P-type region. Among these, the patterning process is generally implemented in three ways: photolithography combined with wet etching, ink printing combined with wet etching, and laser etching.

However, the photolithography method and the wet etching method are not suitable for mass production because of high process cost. In addition, in the process of implementing the patterning process by adopting a laser etching mode, at least the part of the transparent conductive material corresponding to the space where the isolation groove is located needs to be completely removed in order to inhibit electric leakage. The temperature of the processing laser in the laser etching mode is higher, so that the film layer at the bottom of the isolation groove is affected by laser energy, the film layer is damaged, the yield of the back contact solar cell is reduced, and the electrical property of the back contact solar cell is not improved.

In order to solve the technical problems, in a first aspect, an embodiment of the present invention provides a back contact solar cell. As shown in fig. 1, the back contact solar cell includes: a semiconductor substrate, a transparent conductive layer 15, and an insulating light absorbing layer 17. The semiconductor substrate has opposite first and second sides. The second face has N-type regions and P-type regions alternately spaced apart, and isolation regions between each N-type region and the corresponding P-type region. The transparent conductive layer 15 covers the second face. Each isolation region is provided with an isolation groove 16 penetrating through the transparent conductive layer 15, and the isolation groove 16 is used for isolating the part of the transparent conductive layer 15 located on the N-type region from the part of the transparent conductive layer 15 located on the P-type region. As shown in fig. 1 to 4, the insulating light absorbing layer 17 is located at least at the bottom of the isolation groove 16, and the width of the insulating light absorbing layer 17 is equal to or greater than the width of the isolation groove 16.

Specifically, the specific structure of the semiconductor substrate may be set according to the actual application scenario, which is not specifically limited herein.

In the case where the back contact solar cell provided in the embodiment of the present invention is a back contact cell in which the passivation contact structure is not formed on the back surface, the semiconductor substrate may include only a semiconductor substrate, an N-type doped semiconductor layer, and a P-type doped semiconductor layer. The N-type doped semiconductor layer is formed on a portion of the semiconductor substrate corresponding to the N-type region, or alternatively, the N-type doped semiconductor layer may be formed in a portion of the semiconductor substrate corresponding to the N-type region. The P-type doped semiconductor layer is formed on a portion of the semiconductor substrate corresponding to the P-type region, or alternatively, the P-type doped semiconductor layer may be formed in a portion of the semiconductor substrate corresponding to the P-type region. In this case, the N-type region of the semiconductor substrate is a region where the N-type doped semiconductor layer is located, and the P-type region of the semiconductor substrate is a region where the P-type semiconductor layer is located.

Specifically, the semiconductor substrate may be a semiconductor material substrate such as a silicon substrate, a silicon germanium substrate, or a germanium substrate. The semiconductor substrate may be an intrinsic conductive substrate, an N-type conductive substrate, or a P-type conductive substrate in terms of conductivity type. Preferably, the semiconductor substrate is an N-type conductive substrate or a P-type conductive substrate. Compared with the intrinsic conductive substrate, the N-type conductive substrate or the P-type conductive substrate has higher conductivity, is beneficial to reducing the series resistance of the back contact solar cell and improving the photoelectric conversion efficiency of the back contact solar cell. Next, when the N-type doped semiconductor layer and the P-type doped semiconductor layer are formed on portions of the semiconductor substrate corresponding to the N-type region and the P-type region, respectively, the N-type doped semiconductor layer and the P-type doped semiconductor layer may be made of silicon, silicon germanium, silicon carbide, or the like, and the N-type doped semiconductor layer and the P-type doped semiconductor layer may be amorphous, microcrystalline, single crystal, nanocrystalline, polycrystalline, or the like in terms of an internal arrangement form thereof.

In addition, the back contact solar cell provided by the embodiment of the invention can also be a back contact solar cell with a passivation contact structure formed on the backlight surface. In this case, only the N-type region of the semiconductor substrate may be formed with a corresponding passivation contact structure, or only the P-type region of the semiconductor substrate may be formed with a corresponding passivation contact structure, or both the N-type region and the P-type region of the semiconductor substrate may be formed with a corresponding passivation contact structure.

The following description will take an example in which a corresponding passivation contact structure is formed in each of an N-type region and a P-type region of a semiconductor substrate: as shown in fig. 1, the semiconductor base comprises a semiconductor substrate 1, a first semiconductor stack and a second semiconductor stack. The first semiconductor stack is formed at least on a portion of the semiconductor substrate 1 corresponding to the N-type region. The first semiconductor stack comprises a first passivation layer 6, and an N-doped semiconductor layer 7 located on the first passivation layer 6, in a direction away from the semiconductor substrate 1. The second semiconductor stack is formed at least on a portion of the semiconductor substrate 1 corresponding to the P-type region. The second semiconductor stack comprises a second passivation layer 11, and a P-doped semiconductor layer 12 located on the second passivation layer 11, in a direction away from the semiconductor substrate 1. In this case, the first semiconductor stack and the second semiconductor stack are both selective contact structures. Based on the above, the selective contact structure has excellent interface passivation effect and selective collection of carriers, so the first semiconductor lamination and the second semiconductor lamination which are both selective contact structures can further improve the photoelectric conversion efficiency of the back contact solar cell.

The N-type region of the semiconductor substrate is a region where the N-type doped semiconductor layer contacts the transparent conductive layer, and the P-type region of the semiconductor substrate is a region where the P-type semiconductor layer contacts the transparent conductive layer. The isolation regions are regions between each N-type region and an adjacent P-type region.

Specifically, in terms of materials, the materials of the first passivation layer, the N-type doped semiconductor layer, the second passivation layer and the P-type doped semiconductor layer may be determined according to the types of passivation contact structures formed in the N-type region and the P-type region, respectively. For example: when the passivation contact structure formed in the N-type region of the semiconductor substrate is a tunneling passivation contact structure, the first passivation layer is a tunneling passivation layer, and the tunneling passivation layer may be made of one or more of silicon oxide, aluminum oxide, titanium oxide, hafnium oxide, gallium oxide, tantalum pentoxide, niobium pentoxide, silicon nitride, silicon carbonitride, aluminum nitride, titanium nitride, and titanium carbonitride. At this time, the N-type doped semiconductor layer is an N-type doped polysilicon layer. Also for example: when the passivation contact structure formed in the N-type region of the semiconductor substrate is a hetero-contact structure, the first passivation layer is an intrinsic amorphous silicon layer, an intrinsic microcrystalline silicon layer, or a mixed layer of intrinsic microcrystalline silicon and amorphous silicon. At this time, the N-type doped silicon layer is an N-type amorphous silicon layer, an N-type microcrystalline silicon layer, or a mixed layer of N-type amorphous silicon and microcrystalline silicon.

The materials of the second passivation layer and the P-type doped semiconductor layer may be analyzed with reference to the materials of the first passivation layer and the N-type doped semiconductor layer, and will not be described herein.

Second, in terms of passivation species, when the N-type region and the P-type region of the semiconductor substrate are each formed with a corresponding passivation contact structure, the type of passivation contact structure formed by the N-type region and the P-type region may be the same. For example, both the N-type region and the P-type region of the semiconductor substrate may be formed with a tunneling passivation contact structure. Alternatively, both the N-type region and the P-type region of the semiconductor substrate may be formed with a hetero-contact structure.

Of course, when the N-type region and the P-type region of the semiconductor substrate are formed with the corresponding passivation contact structures, the types of passivation contact structures formed by the N-type region and the P-type region may also be different. Illustratively, one of the N-type region and the P-type region of the semiconductor substrate is formed with a tunneling passivation contact structure, and the other is formed with a hetero-contact structure.

In terms of dimensions, the thicknesses of the first passivation layer, the N-type doped semiconductor layer, the second passivation layer, and the P-type doped semiconductor layer may be determined according to the materials of each layer and the actual application scenario, and are not particularly limited herein.

For example: in case the first passivation layer and the second passivation layer are intrinsic amorphous silicon layers, the thickness of the first passivation layer and the second passivation layer may be 3nm to 15nm.

For example: in the case where the N-type doped semiconductor layer is an N-type doped amorphous silicon layer, the thickness of the N-type doped semiconductor layer is 3nm to 20nm.

For example: in the case where the P-type doped semiconductor layer is a P-type doped amorphous silicon layer, the thickness of the P-type doped semiconductor layer is 3nm to 20nm.

In addition, in the case where the semiconductor base includes the above-described semiconductor substrate, the first semiconductor stack, and the second semiconductor stack, the first semiconductor stack may be formed only on a portion of the semiconductor substrate corresponding to the N-type region. Alternatively, as shown in fig. 1, the first semiconductor stack may also be formed on a portion of the semiconductor substrate 1 corresponding to the isolation region. In addition, the second conductor stack may be formed only on a portion of the semiconductor substrate corresponding to the P-type region. Alternatively, as shown in fig. 1, the second semiconductor stack may also be formed on a portion of the semiconductor substrate 1 corresponding to the isolation region.

Specifically, when the first semiconductor stack and the second semiconductor stack are both further formed on the portion of the semiconductor substrate corresponding to the isolation region, as shown in fig. 1, it may be that the first semiconductor stack is further formed directly on the portion of the semiconductor substrate 1 corresponding to the isolation region, and the second semiconductor stack is further formed above the portion of the first semiconductor stack corresponding to the isolation region. At this time, the N-type region of the semiconductor substrate is a region where the N-type doped semiconductor layer 7 is exposed outside the P-type doped semiconductor layer 12, and the P-type region of the semiconductor substrate is a region where the P-type doped semiconductor layer 12 is located. Alternatively, the second semiconductor stack may be further formed directly on a portion of the semiconductor substrate corresponding to the isolation region, and the first semiconductor stack may be further formed over a portion of the second semiconductor stack corresponding to the isolation region. At this time, the N-type region of the semiconductor substrate is a region where the N-type doped semiconductor layer is located, and the P-type region of the semiconductor substrate is a region where the P-type doped semiconductor layer is exposed outside the N-type doped semiconductor layer.

Also, when the first semiconductor stack and the second semiconductor stack are also both formed on the portion of the semiconductor substrate corresponding to the isolation region, the above-described semiconductor substrate may further include an insulating layer 13 as shown in fig. 1, the insulating layer 13 being located between the portion of the first semiconductor stack corresponding to the isolation region and the portion of the second semiconductor stack corresponding to the isolation region. The material and thickness of the insulating layer 13 may be set according to the actual application scenario. For example: the material of the insulating layer 13 may be an insulating material such as silicon oxide or silicon nitride. The thickness of the insulating layer 13 may be 50nm to 500nm.

In the case of the above technical solution, as shown in fig. 1, carriers of the corresponding conductivity type may pass through the first passivation layer 6 and the second passivation layer 11 by tunneling effect, and be collected by the N-type doped semiconductor layer 7 or the P-type doped semiconductor layer 12, respectively. Based on this, when the portion of one of the first semiconductor stack and the second semiconductor stack corresponding to the isolation region is located on the portion of the other corresponding to the isolation region, the insulating layer 13 can isolate the portion of the first semiconductor stack corresponding to the isolation region from the portion of the second semiconductor stack corresponding to the isolation region, preventing carriers from being recombined at the longitudinal boundary of the first semiconductor stack and the second semiconductor stack, and further improving the photoelectric conversion efficiency of the back contact solar cell.

For the transparent conductive layer, the material and thickness of the transparent conductive layer may be set according to the actual application scenario, which is not specifically limited herein. For example: the transparent conductive layer can be made of fluorine doped tin oxide, aluminum doped zinc oxide, tin doped indium oxide, tungsten doped indium oxide, molybdenum doped indium oxide, cerium doped indium oxide or indium hydroxide. For example: the transparent conductive layer may have a thickness of 10nm to 1000nm.

For the above-described isolation trench, the isolation trench may extend through only a portion of the transparent conductive layer on the isolation region. Alternatively, as shown in fig. 1 to 4, the isolation trench 16 may also penetrate the transparent conductive layer 15, and penetrate a portion of the insulating light absorbing layer 17. As for the width of the isolation groove 16, it is possible to set according to the practical application, as long as the portion of the transparent conductive layer 15 located on the N-type region can be isolated from the portion of the transparent conductive layer 15 located on the P-type region by the isolation groove 16.

As shown in fig. 1 to 4, since the insulating light absorbing layer 17 is at least located at the bottom of the isolation groove 16 and the insulating light absorbing layer 17 is a non-conductive film layer, the portion of the transparent conductive layer 15 located on the N-type region and the portion of the transparent conductive layer 15 located on the P-type region cannot be conducted through the insulating light absorbing layer 17, so that the back contact solar cell can be prevented from being shorted. Meanwhile, the insulating light-absorbing layer 17 also has light-absorbing properties. In this case, as shown in fig. 15 to 19, after the transparent conductive layer 15 is formed to cover the entire second surface, even if the isolation groove 16 penetrating the transparent conductive layer 15 is formed on each isolation region by a laser etching process, the presence of the insulating light absorbing layer 17 can reduce or even eliminate damage caused by laser energy to the film layer under the insulating light absorbing layer 17 while ensuring complete penetration of the transparent conductive layer 15, thereby improving the yield of the back contact solar cell. Meanwhile, the problems that the manufacturing cost is high and large-scale mass production is not suitable due to the fact that the isolation groove is formed in the prior art in a mode of combining photoetching with wet etching or in a mode of combining ink printing with wet etching can be solved, the manufacturing cost of the back contact solar cell is reduced, and the mass production of the back contact solar cell is improved.

For example: as shown in fig. 1, in the case where the semiconductor base includes the above-mentioned semiconductor substrate 1, the first semiconductor stack and the second semiconductor stack, since chemical properties of the above-mentioned first passivation layer 6 and second passivation layer 11 are easily changed in a high temperature scenario (e.g., in the case where at least one of the first passivation layer 6 and the second passivation layer 11 is an intrinsic amorphous silicon layer, in the case where the isolation trench 16 is formed by using a laser etching process, the laser energy may cause the intrinsic amorphous silicon layer to be located on the isolation region or a portion located near the isolation region to easily form polycrystalline silicon or monocrystalline silicon, thereby affecting the interface passivation effect of the portion and the selective collection of carriers). Based on this, the presence of the insulating light absorbing layer 17 may reduce or even eliminate damage of the first passivation layer 6 and/or the second passivation layer 11 by the laser, ensuring excellent working performance of the back contact solar cell.

In the above case, the material of the insulating light absorbing layer may be any insulating material having light absorbing properties. For example: the material of the insulating light-absorbing layer may be ink, photoresist, UV-curable glue, or the like. In this case, the ink, the photoresist and the UV curable adhesive all have good light absorption characteristics, so that in the case that the material of the insulating light absorption layer is one of the materials, it is possible to ensure that damage to the portion of the semiconductor substrate corresponding to the isolation region by the laser can be reduced or even eliminated by manufacturing the insulating light absorption material of the insulating light absorption layer during the formation of the isolation trench by the laser etching process.

In terms of morphology, the morphology features such as the width, the thickness, the shape and the like of the insulating light absorption layer can be set according to practical application scenes, so long as the insulating light absorption layer can be applied to the back contact solar cell provided by the embodiment of the invention.

Illustratively, the width of the insulating light absorbing layer may be equal to the width of the isolation trench. At this time, the insulating light absorption layer is located only at the bottom of the isolation groove. In this case, the light absorbing material used for manufacturing the insulating light absorbing layer can be ensured to protect the part of the semiconductor substrate corresponding to the isolation region in the process of forming the isolation groove by adopting the laser etching process, and meanwhile, the consumption of the material used for manufacturing the insulating light absorbing layer can be reduced, and the manufacturing cost of the insulating light absorbing layer can be reduced.

Alternatively, as shown in fig. 1 to 4, the width of the insulating light absorbing layer 17 may be larger than the width of the isolation groove 16. At this time, the insulating light absorption layer 17 is also located between a part of the transparent conductive layer 15 and a part of the semiconductor substrate corresponding to the isolation region. In this case, in the actual manufacturing process, the width of the isolation groove 16 is the etching width of the transparent conductive layer 15 by the laser etching process. Based on this, when the width of the insulating light-absorbing layer 17 is larger than the width of the isolation groove 16, the width of the insulating light-absorbing layer 17 is also larger than the etching width of the transparent conductive layer 15 by the laser etching process. And, the insulating light absorption layer 17 is also located on a portion of the transparent conductive layer 15 and a portion of the semiconductor substrate corresponding to the isolation region. At this time, the presence of the insulating light-absorbing layer 17 can ensure that damage caused by laser etching at the bottom of the isolation trench 16 and at the portion near the corresponding isolation trench 16 of the semiconductor substrate can be reduced or eliminated, and the yield of the back contact solar cell can be further improved.

In the back contact solar cell provided by the embodiment of the invention, the width of the insulating light absorption layer is not particularly limited. Illustratively, the insulating light-absorbing layer may have a width of 5 μm or more and 5mm or less. For example: the width of the insulating light absorbing layer may be 5 μm or more, 100 μm, 300 μm, 600 μm, 900 μm, 2mm, 4mm, 5mm, or the like. In this case, as shown in fig. 1 to 4, the width of the insulating light absorbing layer 17 is equal to or greater than the width of the isolation groove 25. In this regard, in the case where the width of the insulating light absorbing layer 17 is within the above-described range, it is possible to prevent the portion of the transparent conductive layer 15 located on the N-type region from being difficult to separate from the portion of the transparent conductive layer 15 located on the P-type region due to the smaller width of the insulating light absorbing layer 17 making the width of the isolation groove 16 smaller, and suppress electric leakage. Meanwhile, the large consumption of the insulating light absorption layer 17 caused by the large width of the insulating light absorption layer 17 can be prevented, and the manufacturing cost of the insulating light absorption material for manufacturing the insulating light absorption layer 17 is reduced. In addition, the area of the transparent conductive layer 15 covered on the N-type region and the P-type region is reduced due to the fact that the width of the insulating light absorption layer 17 is larger, and carriers generated by the semiconductor substrate in the working state cannot be timely led out by the transparent conductive layer 15, so that the photoelectric conversion efficiency of the back contact solar cell can be improved due to the fact that the width of the insulating light absorption layer 17 is within the range.

In addition, in the practical application process, the thickness of each part of the insulating light absorption layer along the width direction of the isolation region can be the same or different. The actual thickness of each part of the insulating light absorption layer can be determined according to the actual application scene.

As illustrated in fig. 2 to 4, the thickness of both side edge regions of the insulating light absorbing layer 17 may be gradually reduced in the width direction of the isolation groove 16, for example. At this time, the thickness of the insulating light-absorbing layer 17 may be gradually reduced in a linear trend, or may be gradually reduced in a trend of an index, a parabola, or the like. In addition, the degree of gradual decrease in the thickness of the both side edge regions of the insulating light absorbing layer 17 may be set according to actual needs, and is not particularly limited herein.

Under the condition of adopting the technical scheme, when the isolation groove penetrating through the whole transparent conductive layer covered on the second surface is formed by adopting the laser etching process in the actual manufacturing process, the etching strength of the laser on the part of the transparent conductive layer corresponding to the middle part of the isolation groove is larger. On this account, as shown in fig. 2 to 4 and fig. 12 to 14, in the case where the thickness of both side edge regions of the insulating light absorbing layer 17 gradually decreases in the width direction of the isolation groove 16, it is explained that the thickness of the central region in the width direction of the insulating light absorbing material 14 from which the insulating light absorbing layer 17 is manufactured is large. Accordingly, the light absorption property of the insulating light absorption material 14 in the central region in the width direction is strong, so that damage of the laser to the film layer of the semiconductor substrate at the bottom of the isolation trench 16 can be further reduced or even eliminated. In addition, along the width direction of the isolation groove 16, the thickness of the two side edge regions of the insulating light absorption layer 17 is gradually reduced, so that the consumption of materials in the two side edge regions of the insulating light absorption layer 17 can be reduced, and the manufacturing cost of the insulating light absorption layer 17 can be reduced. Meanwhile, the surface of one side of the insulating light absorption layer 17, which is away from the transparent conductive layer 15, is convex, so that the light absorption area of one side of the insulating light absorption layer 17, which is away from the transparent conductive layer 15, can be increased, the unit light absorption amount of one side of the insulating light absorption layer 17, which is away from the transparent conductive layer 15, can be reduced, the damage degree of the laser etching process to the insulating light absorption material 14 for manufacturing the insulating light absorption layer 17 is reduced, the manufacturing thickness of the insulating light absorption material 14 can be reduced finally, and the consumption of materials of the insulating light absorption material 14 is further reduced.

Of course, when the thickness of each portion of the insulating light-absorbing layer in the width direction of the isolation region is different, the insulating light-absorbing layer may also have a morphology in which the edges are thick and the middle is thin. Alternatively, the thickness of the insulating light absorbing layer may also vary in the form of wavy lines or the like. In the above case, the insulating light absorbing layer may have the beneficial effects described above when the surface of the side facing away from the transparent conductive layer is convex.

As a possible implementation, as shown in fig. 4, the side of the insulating light absorbing layer 17 contacting the transparent conductive layer 15 may have at least one light trapping structure. In this case, in the process of forming the isolation groove 16 penetrating through the transparent conductive layer 15 by using the laser etching process, the light trapping structure can enable more laser to be projected into the insulating light absorbing material for manufacturing the insulating light absorbing layer 17, prevent the influence on the appearance of the side wall portion of the transparent conductive layer 15 corresponding to the isolation groove 16 caused by laser scattering, ensure that the appearance of the two side walls of the transparent conductive layer 15 along the width direction of the isolation groove 16 meets the working requirements, further ensure that all the partial regions of the transparent conductive layer 15 along the width direction of the isolation groove 16 have good conductive characteristics, and facilitate the improvement of the photoelectric conversion efficiency of the back contact solar cell.

Specifically, the light trapping structure may be any structure having a light trapping effect, and the shape of the light trapping structure is not particularly limited in the embodiment of the present invention. For example, as shown in fig. 4, the light trapping structure may be a concave structure recessed into the insulating light absorbing layer 17. In this case, in the actual manufacturing process, only screen printing, ink jet or other modes may be adopted, so that the insulating light absorbing material with the light trapping structure having a morphology meeting the working requirements can be formed on the isolation region, no additional processing steps are required for forming the light trapping structure, the manufacturing process of the insulating light absorbing material for manufacturing the insulating light absorbing layer 17 is simplified, and the manufacturing difficulty of the insulating light absorbing material is reduced.

The concave structure may be an inverted cone-shaped concave structure, an inverted trapezoid-shaped concave structure, a hemispherical concave structure or the like, so long as the concave structure has a light trapping effect. As shown in fig. 4, the hemispherical concave structure has a regular shape, and the manufacturing process precision is not strictly required for forming the light trapping structure with a complex shape, so that the manufacturing difficulty of the insulating light absorbing material can be further reduced when the light trapping structure is a hemispherical concave structure. In addition, the hemispherical concave structure is a concave structure with high symmetry, and the surface morphology of each partial area of the surface of the concave structure is the same, so that each partial area of the insulating light absorption material has excellent light trapping effect, and the side wall morphology of the transparent conductive layer along the width direction is further ensured to meet the working requirement.

In addition, in the practical application process, as shown in fig. 1, the back contact solar cell provided in the embodiment of the invention may further include a first electrode 18 and a second electrode 19. Wherein the first electrode 18 is formed on a portion of the transparent conductive layer 15 corresponding to the N-type region. The second electrode 19 is formed on a portion of the transparent conductive layer 15 corresponding to the P-type region. Specifically, the materials of the first electrode 18 and the second electrode 19 may be conductive materials such as copper, silver, and aluminum.

Next, as shown in fig. 1, a passivation anti-reflection layer 10 is formed on the first surface of the semiconductor substrate. Specifically, the material of the passivation anti-reflection layer 10 may be silicon nitride, silicon oxynitride, silicon oxide, or the like. The thickness of the anti-reflection layer may be 50nm to 200nm. Of course, the thickness of the passivation anti-reflection layer 10 may be set to other suitable values according to different application scenarios.

In a second aspect, embodiments of the present invention further provide a photovoltaic module, where the photovoltaic module includes the back contact solar cell provided in the first aspect and various implementations thereof.

The beneficial effects of the second aspect of the embodiments of the present invention may refer to the beneficial effect analysis in the first aspect and various implementation manners thereof, which are not described herein.

In a third aspect, the embodiment of the invention further provides a method for manufacturing the back contact solar cell. Hereinafter, the manufacturing process will be described with reference to cross-sectional views of the operation shown in fig. 2 to 20. Specifically, the method for manufacturing the back contact solar cell comprises the following steps:

first, as shown in fig. 10, a semiconductor substrate is formed. The semiconductor substrate has opposite first and second sides. The second face has N-type regions and P-type regions alternately spaced apart, and isolation regions between each N-type region and the corresponding P-type region.

Specifically, the specific structure and materials of the semiconductor substrate may be referred to the foregoing, and will not be described herein. In addition, it is understood that when the structures of the semiconductor substrates are different, the corresponding manufacturing processes of the semiconductor substrates are also different.

For example, as shown in fig. 1, when the semiconductor base includes the above-described semiconductor substrate 1, the first semiconductor stack, and the second semiconductor stack, the manufacturing process of the semiconductor base may include the steps of: first, a semiconductor substrate is provided. The material of the semiconductor substrate may be referred to above. Next, a first semiconductor stack may be formed on at least a portion of the semiconductor substrate corresponding to the N-type region using deposition, etching, and the like. The first semiconductor lamination comprises a first passivation layer and an N-type doped semiconductor layer positioned on the first passivation layer along the direction away from the semiconductor substrate. Next, a second semiconductor stack may be formed on at least a portion of the semiconductor substrate corresponding to the P-type region using deposition, etching, and the like. The second semiconductor lamination comprises a second passivation layer and a P-type doped semiconductor layer positioned on the second passivation layer along the direction away from the semiconductor substrate.

It should be noted that, the manufacturing sequence of the first semiconductor stack and the second semiconductor stack of the back contact solar cell provided in the embodiment of the present invention is not specifically limited. The specific formation sequence of the two can be determined according to the structure of the back contact solar cell and the actual application scene.

In addition, on the portion of the first semiconductor layer stack corresponding to the isolation region of the semiconductor substrate, the second semiconductor layer stack is further formed above the portion of the first semiconductor layer stack corresponding to the isolation region; or, in a case where the second semiconductor stack is further formed on a portion of the semiconductor substrate corresponding to the isolation region and the first semiconductor stack is further formed above a portion of the second semiconductor stack corresponding to the isolation region, the method for manufacturing the back contact solar cell further includes: an insulating layer is formed between a portion of the first semiconductor stack corresponding to the isolation region and a portion of the second semiconductor stack corresponding to the isolation region.

The process of manufacturing the back contact solar cell will be described in detail below taking an example in which the second semiconductor stack is further formed on a portion of the first semiconductor stack corresponding to the isolation region, and the back contact solar cell further includes an insulating layer:

As shown in fig. 5, a first passivation material layer 2, an N-type doped semiconductor material layer 3, an insulating material layer 4, and a mask material layer that are stacked in this order may be formed on the back surface of the semiconductor substrate 1 in the thickness direction of the semiconductor substrate by using a process such as plasma enhanced chemical vapor deposition. Then, as shown in fig. 6, the mask material layer may be patterned by using a process such as laser etching, so that only the portion of the mask material layer covering the portion of the semiconductor substrate 1 corresponding to the N-type region is remained, and the remaining portion of the mask material layer forms a mask layer 5; and under the mask action of the mask layer, patterning the insulating material layer, the N-type doped semiconductor material layer and the first passivation material layer by adopting wet etching and other processes, and removing at least the parts of the three film layers on the corresponding P-type region of the semiconductor substrate, so that the rest part of the N-type doped semiconductor material layer forms an N-type doped semiconductor layer and the rest part of the first passivation material layer forms a first passivation layer. The mask layer is then removed as shown in fig. 7. Next, as shown in fig. 8, a second passivation material layer 8 and a P-type doped semiconductor material layer 9 covering the backlight surface may be sequentially formed in a direction away from the semiconductor substrate 1 by using a process such as a plasma enhanced chemical vapor deposition; and a passivation anti-reflection layer 10 is formed on the light-facing surface of the semiconductor substrate 1. The order of forming the second passivation layer 8 and the P-type doped semiconductor layer 9, and the passivation anti-reflection layer 10 may be determined according to the actual application scenario, and is not specifically limited herein. Then, as shown in fig. 10, portions of the second passivation material layer and the P-type doped semiconductor material layer located on the N-type region may be selectively removed by photolithography in combination with wet etching or the like, so that the remaining portion of the second passivation material layer forms the second passivation layer 11 and the remaining portion of the P-type doped semiconductor material layer forms the P-type doped semiconductor layer 12. As shown in fig. 10, under the mask effect of the P-type doped semiconductor layer 12 and the second passivation layer 11, the exposed portion of the insulating material layer is removed by wet etching, so that the remaining portion of the insulating material layer forms an insulating layer 13, thereby obtaining a semiconductor substrate.

It should also be noted that the semiconductor substrate described above may be formed in a variety of ways. How the above-described semiconductor substrate is formed is not a main feature of the present invention, and thus, in the present specification, it is only briefly described so that one of ordinary skill in the art can easily implement the present invention. Other ways of fabricating the above-described semiconductor substrate are well within the contemplation of those of ordinary skill in the art.

Next, as shown in fig. 11 to 14, an insulating light absorbing material 14 is formed on at least part of the isolation region.

In an actual manufacturing process, a photolithography process, a screen printing process, an inkjet printing process, or the like may be used to form the insulating light absorbing material. Among them, since the screen printing process and the inkjet printing process are conventional processes for manufacturing the back contact solar cell, when the insulating light absorbing material is formed using the screen printing process or the inkjet printing process, a separately manufactured apparatus for forming the insulating light absorbing material is not required. In other words, the manufacturing method of the back contact solar cell provided by the embodiment of the invention can be compatible with the conventional manufacturing process and equipment of the conventional back contact solar cell, reduce the manufacturing difficulty of the back contact solar cell and improve the manufacturing efficiency.

In addition, the insulating light absorption layer is formed after the insulating light absorption material is processed by a subsequent laser etching process. Based on this, the foregoing topographical features, such as the material and width, of the insulating light absorbing layer may be referenced to determine the corresponding features of the insulating light absorbing material, which will not be described herein.

Specifically, as shown in fig. 11, the top surface area of the portion of the insulating light absorbing material 14 corresponding to the isolation trench may be equal to the bottom surface area of the portion of the insulating light absorbing material 14 corresponding to the isolation trench. At this time, the top and bottom surfaces of the insulating light absorbing material 14 are both planes parallel to the back surface of the semiconductor substrate 1. Alternatively, as shown in fig. 12 to 14, the top surface area of the portion of the insulating light absorbing material 14 corresponding to the isolation trench may be larger than the bottom surface area of the portion of the insulating light absorbing material 14 corresponding to the isolation trench. In this case, the specific surface area of the top surface of the insulating light absorbing material 14 is larger, so that the unit light absorbing amount of the side of the insulating light absorbing material 14 away from the transparent conductive layer can be reduced, the damage degree of the subsequent laser etching process to the insulating light absorbing material 14 for manufacturing the insulating light absorbing layer is reduced, the manufacturing thickness of the insulating light absorbing material 14 can be reduced finally, and the consumption of materials of the insulating light absorbing material 14 is further reduced.

In addition, the insulating light absorbing material may have a morphology with thick sides and thin middle along the width direction of the isolation region. At this time, the average thickness of the both side edge regions of the insulating light absorbing material is greater than that of the intermediate region thereof in the width direction of the isolation region. Alternatively, as shown in fig. 12 to 14, the insulating light absorbing material 14 may have a shape with a thick middle and thin sides. At this time, the average thickness of the middle region of the insulating light absorbing material 14 is greater than the average thickness of the both side edge regions of the insulating light absorbing material 14 in the width direction of the isolation groove.

The specific thickness of the insulating light absorbing material may be determined according to the actual application scenario, and is not specifically limited herein. Illustratively, the minimum thickness of the portion of the insulating light absorbing material corresponding to the isolation trench is 0.05 μm or more and 100 μm or less. For example: the minimum thickness of the portion of the insulating light absorbing material corresponding to the isolation groove is 0.05 μm, 10 μm, 30 μm, 60 μm, 90 μm, 100 μm, or the like. In this case, the minimum thickness of the portion of the insulating light-absorbing material corresponding to the isolation groove is within the above range, so that the portion of the insulating light-absorbing material corresponding to the isolation groove can be prevented from being completely etched by laser before the portion of the insulating light-absorbing material corresponding to the isolation groove is not completely etched to penetrate through the transparent conductive layer, the portion of the insulating light-absorbing material corresponding to the isolation region of the semiconductor substrate can be protected in the whole etching process, and the high yield of the back contact solar cell can be further ensured. Meanwhile, the consumption of the insulating light absorbing material is prevented from being large due to the fact that the minimum thickness is large, and the manufacturing cost of the insulating light absorbing material is reduced.

Next, in a practical application process, as shown in fig. 14, a side of the insulating light absorbing material 14 facing away from the semiconductor substrate may be provided with a plurality of light trapping structures. The specific shape of the light trapping structure can refer to the shape of the light trapping structure arranged on the insulating light absorbing layer, which is not described herein.

The plurality of light trapping structures may be disposed at random on a side of the insulating material facing away from the semiconductor substrate. Preferably, as shown in fig. 14, the plurality of light trapping structures are uniformly distributed on the side of the insulating light absorbing material 14 facing away from the semiconductor substrate. In this case, the light trapping effect of each portion of the insulating light absorbing material 14 is substantially the same, so that the regions of the semiconductor substrate covered by each portion of the insulating light absorbing material 14 can be effectively protected, and the yield of the back contact solar cell can be further improved.

Next, after the insulating light absorbing material is formed, as shown in fig. 15 to 18, a physical vapor deposition process or the like may be used to form a transparent conductive layer 15 entirely covering the N-type region, the P-type region, and the insulating light absorbing material 14. In particular, information such as the material and thickness of the transparent conductive layer 15 may be referred to above.

Then, as shown in fig. 19, an isolation groove 16 penetrating the transparent conductive layer 15 is formed on each isolation region using a laser etching process, and the remaining insulating light absorbing material is made to form an insulating light absorbing layer 17. The isolation trench 16 is used to isolate the portion of the transparent conductive layer 15 located on the N-type region from the portion of the transparent conductive layer 15 located on the P-type region. The insulating light-absorbing layer 17 is at least located at the bottom of the isolation groove 16, and the width of the insulating light-absorbing layer 17 is greater than or equal to the width of the isolation groove 16.

Specifically, the working parameters of the laser etching process may be determined according to the actual application scenario, which is not specifically limited herein.

As shown in fig. 20, the first electrode 18 may be formed on a portion of the transparent conductive layer 15 corresponding to the N-type region, and the second electrode 19 may be formed on a portion of the transparent conductive layer 15 corresponding to the P-type region, by screen printing or plating. The materials of the first electrode 18 and the second electrode 19 may be referred to as above, and will not be described herein.

The beneficial effects of the third aspect and various implementations of the embodiments of the present invention may refer to the beneficial effect analysis in the first aspect and various implementations thereof, which are not described herein.

In the above description, technical details of patterning, etching, and the like of each layer are not described in detail. Those skilled in the art will appreciate that layers, regions, etc. of the desired shape may be formed by a variety of techniques. In addition, to form the same structure, those skilled in the art can also devise methods that are not exactly the same as those described above. In addition, although the embodiments are described above separately, this does not mean that the measures in the embodiments cannot be used advantageously in combination.

The embodiments of the present disclosure are described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be made by those skilled in the art without departing from the scope of the disclosure, and such alternatives and modifications are intended to fall within the scope of the disclosure.

Claims

1. A back contact solar cell, comprising:

a semiconductor substrate having opposite first and second sides; the second surface is provided with N-type regions and P-type regions which are alternately distributed at intervals, and isolation regions positioned between each N-type region and the corresponding P-type region;

a transparent conductive layer covering the second face; each isolation region is provided with an isolation groove penetrating through the transparent conductive layer, and the isolation groove is used for isolating the part of the transparent conductive layer on the N-type region from the part of the transparent conductive layer on the P-type region;

the insulating light absorption layer is at least positioned at the bottom of the isolation groove, and the width of the insulating light absorption layer is larger than or equal to the width of the isolation groove.

2. The back contact solar cell of claim 1, wherein the width of the insulating light absorbing layer is greater than the width of the isolation trench;

the insulating light absorption layer is also positioned between a part of the transparent conductive layer and a part of the semiconductor substrate corresponding to the isolation region.

3. The back contact solar cell according to claim 2, wherein the thickness of both side edge regions of the insulating light absorbing layer is gradually reduced in the width direction of the isolation trench.

4. The back contact solar cell of claim 2, wherein a side of the insulating light absorbing layer in contact with the transparent conductive layer has at least one light trapping structure.

5. The back contact solar cell of claim 4, wherein the light trapping structure is a recessed structure recessed into the insulating light absorbing layer.

6. The back contact solar cell of claim 5, wherein the recessed structures are hemispherical recessed structures.

7. The back contact solar cell according to claim 1, wherein the width of the insulating light absorbing layer is 5 μm or more and 5mm or less; and/or the number of the groups of groups,

The material of the insulating light absorption layer is ink, photoresist or UV curing adhesive.

8. The back contact solar cell of any one of claims 1-6, wherein the semiconductor substrate comprises: a semiconductor substrate having a semiconductor layer formed thereon,

a first semiconductor stack formed at least on a portion of the semiconductor substrate corresponding to the N-type region; the first semiconductor lamination comprises a first passivation layer and an N-type doped semiconductor layer positioned on the first passivation layer along the direction away from the semiconductor substrate;

a second semiconductor stack formed at least on a portion of the semiconductor substrate corresponding to the P-type region; the second semiconductor stack includes a second passivation layer and a P-type doped semiconductor layer on the second passivation layer in a direction away from the semiconductor substrate.

9. The back contact solar cell of claim 8, wherein the first semiconductor stack is further formed on a portion of the semiconductor substrate corresponding to the isolation region, the second semiconductor stack is further formed over a portion of the first semiconductor stack corresponding to the isolation region; or, the second semiconductor lamination is further formed on a part of the semiconductor substrate corresponding to the isolation region, and the first semiconductor lamination is further formed above a part of the second semiconductor lamination corresponding to the isolation region;

The semiconductor substrate further includes an insulating layer between a portion of the first semiconductor stack corresponding to the isolation region and a portion of the second semiconductor stack corresponding to the isolation region.

10. A photovoltaic module comprising a back contact solar cell according to any one of claims 1 to 9.

11. A method of manufacturing a back contact solar cell, comprising:

forming a semiconductor substrate; the semiconductor substrate has opposite first and second sides; the second surface is provided with N-type regions and P-type regions which are alternately distributed at intervals, and isolation regions positioned between each N-type region and the corresponding P-type region;

forming an insulating light absorbing material over at least a portion of the isolation region;

forming a transparent conductive layer which covers the N-type region, the P-type region and the insulating light absorption material;

forming an isolation groove penetrating through the transparent conductive layer on each isolation area by adopting a laser etching process, and enabling the rest insulating light absorption material to form an insulating light absorption layer; the isolation groove is used for isolating the part of the transparent conducting layer on the N-type region from the part of the transparent conducting layer on the P-type region; the insulating light absorption layer is at least positioned at the bottom of the isolation groove, and the width of the insulating light absorption layer is greater than or equal to the width of the isolation groove.

12. The method of claim 11, wherein a top surface area of the portion of the insulating light absorbing material corresponding to the isolation trench is greater than a bottom surface area of the portion of the insulating light absorbing material corresponding to the isolation trench.

13. The method of manufacturing a back contact solar cell according to claim 11 or 12, wherein an average thickness of the middle region of the insulating light absorbing material is greater than an average thickness of both side edge regions of the insulating light absorbing material in a width direction of the isolation trench.

14. The method of claim 11, wherein a side of the insulating light absorbing material facing away from the semiconductor substrate is provided with a plurality of light trapping structures.

15. The method of claim 14, wherein the plurality of light trapping structures are uniformly distributed on a side of the insulating light absorbing material facing away from the semiconductor substrate.

16. The method of claim 11, wherein the insulating light absorbing material is formed using a screen printing process or an inkjet printing process; and/or the number of the groups of groups,

The minimum thickness of the part of the insulating light absorbing material corresponding to the isolation groove is more than or equal to 0.05 mu m and less than or equal to 100 mu m.

17. The method of claim 11, wherein forming a semiconductor substrate comprises:

providing a semiconductor substrate;

forming a first semiconductor lamination at least on a part of the semiconductor substrate corresponding to the N-type region; the first semiconductor lamination comprises a first passivation layer and an N-type doped semiconductor layer positioned on the first passivation layer along the direction away from the semiconductor substrate;

forming a second semiconductor lamination layer at least on a part of the semiconductor substrate corresponding to the P-type region; the second semiconductor lamination comprises a second passivation layer and a P-type doped semiconductor layer positioned on the second passivation layer along the direction away from the semiconductor substrate; the semiconductor base includes the semiconductor substrate, the first semiconductor stack, and the second semiconductor stack.

18. The method of claim 17, wherein the first semiconductor stack is further formed on a portion of the semiconductor substrate corresponding to the isolation region, and the second semiconductor stack is further formed over a portion of the first semiconductor stack corresponding to the isolation region; or, the second semiconductor lamination is further formed on a part of the semiconductor substrate corresponding to the isolation region, and the first semiconductor lamination is further formed above a part of the second semiconductor lamination corresponding to the isolation region;

The method for manufacturing the back contact solar cell further comprises the steps of:

an insulating layer is formed between a portion of the first semiconductor stack corresponding to the isolation region and a portion of the second semiconductor stack corresponding to the isolation region.