CN114171627A

CN114171627A - Heterojunction solar cell and manufacturing method thereof

Info

Publication number: CN114171627A
Application number: CN202010847959.4A
Authority: CN
Inventors: 张达奇; 姚铮; 吴华德; 吴坚; 蒋方丹
Original assignee: Jiaxing Canadian Solar Technology Research Institute
Current assignee: Jiaxing Canadian Solar Technology Research Institute
Priority date: 2020-08-21
Filing date: 2020-08-21
Publication date: 2022-03-11

Abstract

The invention provides a heterojunction solar cell and a manufacturing method thereof, wherein the side surface of a monocrystalline silicon substrate of the heterojunction solar cell is provided with an amorphous layer.

Description

Heterojunction solar cell and manufacturing method thereof

Technical Field

The invention relates to the field of photovoltaic manufacturing, in particular to a heterojunction solar cell and a manufacturing method thereof.

Background

The heterojunction solar cell is a relatively high-efficiency crystalline silicon solar cell at present, combines the characteristics of a crystalline silicon cell and a silicon-based thin film cell, and has the advantages of short manufacturing process, low process temperature, high conversion efficiency, more generated energy and the like. Fig. 1 is a schematic structural diagram of a heterojunction solar cell in the prior art, which sequentially includes, from top to bottom, a first collector electrode 51 ', a first transparent conductive film 41 ', a first doped amorphous layer 31 ', a first intrinsic amorphous layer 21 ', a single crystal silicon substrate 10 ', a second intrinsic amorphous layer 22 ', a second doped amorphous layer 32 ', a second transparent conductive film 42 ', and a second collector electrode 52 '.

In the specific manufacturing process of the heterojunction solar cell in the prior art, the manufacturing of four amorphous layers, namely a first intrinsic amorphous layer 21 ', a second intrinsic amorphous layer 22 ', a first doped amorphous layer 31 ' and a second doped amorphous layer 32 ', on two surfaces of a monocrystalline silicon substrate 10 ' is generally completed through a PECVD process; then, the first transparent conductive film layer 41 'and the second transparent conductive film layer 42' are manufactured by the PVD process; finally, the first collector electrode 51 'and the second collector electrode 52' are manufactured by a screen printing process.

In the specific process of fabricating the four amorphous layers, the prior art needs to arrange the metal mask such that the first intrinsic amorphous layer 21 ', the second intrinsic amorphous layer 22', the first doped amorphous layer 31 ', and the second doped amorphous layer 32' are formed on only two major surfaces of the single crystal silicon substrate 10 ', i.e. the first intrinsic amorphous layer 21', the second intrinsic amorphous layer 22 ', the first doped amorphous layer 31', and the second doped amorphous layer 32 'do not extend to the side of the single crystal silicon substrate 10'.

However, the heterojunction solar cell related to the prior art has the following problems: the side surface of the monocrystalline silicon substrate 10 'is not shielded by an amorphous layer, and the first transparent conductive film layer 41' and the second transparent conductive film layer 42 'are easily in direct contact with the monocrystalline silicon substrate 10', so that the risk of electric leakage exists; direct edge exposure of the single crystal silicon substrate 10' increases the risk of edge damage; the edge region of the single crystal silicon substrate 10' is insufficiently passivated.

In view of the above, there is a need to provide an improved solution to the above problems.

Disclosure of Invention

The present invention is designed to solve at least one of the problems of the prior art, and to achieve the above object, the present invention provides a heterojunction solar cell, which is specifically designed as follows.

A heterojunction solar cell comprises a monocrystalline silicon substrate, wherein the monocrystalline silicon substrate is provided with a first main surface and a second main surface which are arranged in an opposite way, and a side surface connecting the first main surface and the second main surface, one of the first main surface and the second main surface is a light receiving surface, and the other one of the first main surface and the second main surface is a backlight surface; the heterojunction solar cell further comprises a first intrinsic amorphous layer, a first doped amorphous layer, a first transparent conductive film layer and a first collector which are sequentially arranged on one side of the first main surface, and a second intrinsic amorphous layer, a second doped amorphous layer, a second transparent conductive film layer and a second collector which are sequentially arranged on one side of the second main surface, wherein the first intrinsic amorphous layer is provided with a first intrinsic side portion which extends towards the direction of the second intrinsic amorphous layer to cover the whole side surface, the second intrinsic amorphous layer is provided with a second intrinsic side portion which extends towards the direction of the first intrinsic amorphous layer to cover the first intrinsic side portion, and the first doped amorphous layer and the second doped amorphous layer are opposite in doping type and are provided with doped side portions which extend out of the side surface and are mutually connected.

Further, the sum of the thicknesses of the first intrinsic amorphous layer, the first doped amorphous layer, the second intrinsic amorphous layer and the second doped amorphous layer on the light receiving surface is less than or equal to the sum of the thicknesses of the first intrinsic amorphous layer, the first doped amorphous layer, the second doped amorphous layer and the second doped amorphous layer on the backlight surface.

Further, the sum of the thicknesses of the first intrinsic amorphous layer, the first doped amorphous layer, the second intrinsic amorphous layer and the second doped amorphous layer on the light receiving surface is 6-21nm, and the sum of the thicknesses of the first intrinsic amorphous layer, the second doped amorphous layer and the second doped amorphous layer on the backlight surface is 6-30 nm.

Further, the thickness of the first intrinsic amorphous layer and the second intrinsic amorphous layer on the light receiving surface is smaller than or equal to the thickness of the second intrinsic amorphous layer on the backlight surface.

Furthermore, the thickness of the first intrinsic amorphous layer and the second intrinsic amorphous layer on the light receiving surface is 3-6nm, and the thickness of the first intrinsic amorphous layer and the second intrinsic amorphous layer on the backlight surface is 3-10 nm.

Further, the thickness of the first doped amorphous layer and the second doped amorphous layer on the light receiving surface side is smaller than or equal to the thickness of the second doped amorphous layer on the backlight surface side.

Further, the thickness of the first doped amorphous layer and the second doped amorphous layer on one side of the light receiving surface is 3-15nm, and the thickness of the first doped amorphous layer and the second doped amorphous layer on one side of the backlight surface is 3-20 nm.

Further, the oxygen content of the first doped amorphous layer and the second doped amorphous layer on the light receiving surface is greater than or equal to the oxygen content on one side of the backlight surface.

Furthermore, in a direction from the backlight surface to the light receiving surface, the first doped amorphous layer and the second doped amorphous layer, which are located on the light receiving surface, sequentially include a first doped amorphous silicon film and a doped amorphous silicon oxide film, a doped amorphous silicon carbide film or a doped amorphous silicon carbide/doped amorphous silicon oxide composite film, which are located on the surface of the first doped amorphous silicon film.

Further, the first doped amorphous layer and the second doped amorphous layer on the light receiving surface further include a second doped amorphous silicon film on the surface of the doped amorphous silicon oxide film, the doped amorphous silicon carbide film or the doped amorphous silicon carbide/doped amorphous silicon oxide composite film.

Furthermore, in a direction from the light receiving surface to the backlight surface, a third doped amorphous silicon film and a fourth doped amorphous silicon film, which is located on the surface of the third doped amorphous silicon film and has a doping concentration greater than that of the third doped amorphous silicon film, are sequentially included in the first doped amorphous layer and the second doped amorphous layer, which are located on the backlight surface.

Further, the doped side edge portion of the first doped amorphous layer and the doped side edge portion of the second doped amorphous layer are stacked outside the second intrinsic side edge portion.

Further, the sum of the thicknesses of the parts of the first intrinsic side edge part and the second intrinsic side edge part covering the first intrinsic side edge part, and the thickness of the part of the second intrinsic side edge part covering the side face and the side face connecting with the second main face are not less than 1 nm.

Further, the first intrinsic amorphous layer and the second intrinsic amorphous layer respectively include at least two stacked intrinsic films, and each intrinsic film is formed by one of intrinsic amorphous silicon, intrinsic amorphous silicon oxide, and intrinsic amorphous silicon carbide.

Further, one layer of the intrinsic film, which is farthest from the single crystal silicon substrate, of the first intrinsic amorphous layer and/or the second intrinsic amorphous layer is intrinsic amorphous silicon oxide.

Further, the hydrogen content of the intrinsic film close to the monocrystalline silicon substrate in the first intrinsic amorphous layer is higher than that of the intrinsic film far away from the monocrystalline silicon substrate, and the hydrogen content of the intrinsic film close to the monocrystalline silicon substrate in the second intrinsic amorphous layer is higher than that of the intrinsic film far away from the monocrystalline silicon substrate.

Furthermore, the first intrinsic amorphous layer and the second intrinsic amorphous layer respectively comprise three layers of intrinsic films which are stacked, and the hydrogen content ranges of the three layers of intrinsic films of the first intrinsic amorphous layer and the second intrinsic amorphous layer are respectively 20% -40%, 10% -25% and 8% -20% in sequence in the direction far away from the monocrystalline silicon substrate.

Further, the monocrystalline silicon substrate is n-type monocrystalline silicon, the n-type doped amorphous layer is positioned on one side of the light receiving surface in the first doped amorphous layer and the second doped amorphous layer, and the p-type doped amorphous layer is positioned on one side of the backlight surface in the first doped amorphous layer and the second doped amorphous layer.

Further, the first transparent conductive film layer and the second transparent conductive film layer are positioned on the light receiving surface and comprise a first TCO film attached to the surface of the n-type doped amorphous layer and a second TCO film attached to the surface of the first TCO film, and the mass ratio of doped oxides in the first TCO film is larger than that of doped oxides in the second TCO film.

Further, the mass percentage of the doped oxide in the first TCO film is 5% -20%, and the mass percentage of the doped oxide in the second TCO film is 0.5% -5%.

Further, the first transparent conductive film layer and the second transparent conductive film layer are positioned on the light receiving surface and further comprise a third TCO film attached to the surface of the second TCO film, and the mass ratio of doped oxides in the third TCO film is larger than that of the doped oxides in the second TCO film.

Further, the first transparent conductive film layer and the second transparent conductive film layer are located on the backlight surface and comprise a fourth TCO film attached to the surface of the p-type doped amorphous layer and a fifth TCO film attached to the surface of the fourth TCO film, and the mass ratio of doped oxides in the fourth TCO film is smaller than that of the doped oxides in the fifth TCO film.

Further, the thicknesses of the first transparent conductive film layer and the second transparent conductive film layer on the light receiving surface are less than or equal to the thicknesses of the first transparent conductive film layer and the second transparent conductive film layer on the backlight surface.

Further, one of the first and second transparent conductive film layers extends out of the side surface to cover the doped side edge portion.

The invention also provides a method for manufacturing a heterojunction solar cell, which is used for manufacturing the heterojunction solar cell, and comprises the following steps:

a monocrystalline silicon substrate texturing step, wherein texturing is carried out on a first main surface, a second main surface and side surfaces of the monocrystalline silicon substrate;

a first intrinsic amorphous layer manufacturing step of placing the monocrystalline silicon substrate with the first main surface upward on a first carrier plate, wherein the first carrier plate is provided with a first groove for placing the monocrystalline silicon substrate, the first intrinsic amorphous layer is formed by deposition on the first main surface side of the monocrystalline silicon substrate from the upper side of the first carrier plate, and the periphery of the first intrinsic amorphous layer extends to cover all the side surfaces;

a second intrinsic amorphous layer manufacturing step of placing the monocrystalline silicon substrate after the first intrinsic amorphous layer manufacturing step with the second main surface upward on a second carrier plate, wherein the second carrier plate is provided with a second groove for placing the monocrystalline silicon substrate, a second intrinsic amorphous layer is formed by deposition on the second main surface side of the monocrystalline silicon substrate from the upper side of the second carrier plate, and the periphery of the second intrinsic amorphous layer extends to cover the first intrinsic side edge part;

a first doped amorphous layer manufacturing step of placing the monocrystalline silicon substrate after the second intrinsic amorphous layer manufacturing step with the first main surface upward on a third carrier plate, wherein the third carrier plate is provided with a third groove for placing the monocrystalline silicon substrate, the first doped amorphous layer is formed on the first intrinsic amorphous layer from the upper side of the third carrier plate, and a first doped side edge part extending out of the side surface is formed on the first doped amorphous layer;

a second doped amorphous layer manufacturing step of placing the monocrystalline silicon substrate after the second intrinsic amorphous layer manufacturing step on a fourth carrier plate with a second main surface facing upwards, wherein the fourth carrier plate is provided with a fourth groove for placing the monocrystalline silicon substrate, the first doped amorphous layer is formed on the second intrinsic amorphous layer from the upper side of the fourth carrier plate, the second doped amorphous layer is formed with a second doped side edge part which extends out of the side surface and is connected with the first doped side edge part, and the sequence of the second doped amorphous layer manufacturing step and the first doped amorphous layer manufacturing step is adjustable;

a transparent conductive film layer manufacturing step of depositing the first main surface side and the second main surface side of the monocrystalline silicon substrate after the first doped amorphous layer manufacturing step and the second doped amorphous layer manufacturing step are completed respectively to form a first transparent conductive film layer and a second transparent conductive film layer;

and a collector manufacturing step, wherein a first collector is formed on the surface of one side of the first transparent conductive film layer, which is far away from the first doped amorphous layer, and a second collector is formed on the surface of one side of the second transparent conductive film layer, which is far away from the second doped amorphous layer.

Further, the difference range between the side length of the first groove, the second groove, the third groove and the fourth groove and the corresponding side length of the monocrystalline silicon substrate is less than 2 mm.

The invention has the beneficial effects that: based on the heterojunction solar cell provided by the invention, the electric leakage caused by the direct contact formed between the first transparent conductive film layer and the monocrystalline silicon substrate and between the second transparent conductive film layer and the monocrystalline silicon substrate can be avoided, and the risk of damaging the edge of the monocrystalline silicon substrate is reduced; the side surface of the monocrystalline silicon substrate is covered by the first intrinsic side edge part and the second intrinsic side edge part, so that the passivation effect of the side surface of the monocrystalline silicon substrate can be effectively improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic diagram of a prior art heterojunction solar cell;

FIG. 2 is a schematic diagram of a first embodiment of a heterojunction solar cell of the invention;

FIG. 3 is a partial schematic view of a first embodiment of a heterojunction solar cell of the embodiment shown in FIG. 2;

FIG. 4 is a partial schematic view of a second embodiment of a heterojunction solar cell of the embodiment shown in FIG. 2;

FIG. 5 is a partial schematic view of a third embodiment of a heterojunction solar cell of the embodiment shown in FIG. 2;

FIG. 6 is a partial schematic view of a fourth embodiment of a heterojunction solar cell of the embodiment shown in FIG. 2;

FIG. 7 is a partial schematic view of a fifth embodiment of a heterojunction solar cell of the embodiment shown in FIG. 2;

FIG. 8 is a schematic view of a second embodiment of a heterojunction solar cell of the invention;

FIG. 9 is a schematic view of a third embodiment of a heterojunction solar cell of the invention;

FIG. 10 is a schematic diagram of a fourth embodiment of a heterojunction solar cell of the invention;

FIG. 11 is a schematic view of a fifth embodiment of a heterojunction solar cell of the invention;

FIG. 12 is a state diagram illustrating the fabrication of a first intrinsic amorphous layer in a heterojunction solar cell of the invention;

FIG. 13 is a state diagram illustrating the fabrication of a second intrinsic amorphous layer in a heterojunction solar cell of the invention;

FIG. 14 is a schematic diagram illustrating a state of a first doped amorphous layer in a heterojunction solar cell of the invention;

FIG. 15 is a schematic diagram illustrating a state of a second doped amorphous layer in a heterojunction solar cell of the invention;

fig. 16 is a schematic diagram illustrating a state of the transparent conductive film layer in the heterojunction solar cell of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 2, 8, 9, 10 and 11, the heterojunction solar cell according to the present invention includes a single-crystal silicon substrate 10, a first intrinsic amorphous layer 21, a first doped amorphous layer 31, a first transparent conductive film layer 41, a first collector 51, a second intrinsic amorphous layer 22, a second doped amorphous layer 32, a second transparent conductive film layer 42 and a second collector 52. The first intrinsic amorphous layer 21, the first doped amorphous layer 31, the first transparent conductive film layer 41, and the first collector 51 are sequentially disposed on the first main surface side, and the second intrinsic amorphous layer 22, the second doped amorphous layer 32, the second transparent conductive film layer 42, and the second collector 52 are sequentially disposed on the second main surface side.

The single crystal silicon substrate 10 according to the present invention has a first main surface and a second main surface which are opposed to each other, and a side surface connecting the first main surface and the second main surface. One of the first main surface and the second main surface is a light receiving surface, and the other is a backlight surface.

Referring to fig. 2, 8, 9, 10, 11, in the present invention, the first intrinsic amorphous layer 21 has a first intrinsic side portion 210 extending toward the second intrinsic amorphous layer 22, the first intrinsic side portion 210 extending peripherally to cover the entire side of the single crystal silicon substrate 10; that is, the first intrinsic amorphous layer 21 has a region covering all the side surfaces in addition to the region covering the first main surface. The second intrinsic amorphous layer 22 has a second intrinsic side portion 220 extending toward the first intrinsic amorphous layer 21 to cover the first intrinsic side portion 210; that is, the second intrinsic amorphous layer 22 has a portion located outside the first intrinsic side edge portion 210 in addition to the region overlying the second main surface.

The first doped amorphous layer 31 and the second doped amorphous layer 32 according to the present invention each have doped side portions extending out of the side surfaces and forming a connection with each other.

Based on the heterojunction solar cell provided by the invention, the direct contact between the first transparent conductive film layer 41 and the second transparent conductive film layer 42 and the monocrystalline silicon substrate 10 can be avoided to cause electric leakage, and the risk of damaging the edge of the monocrystalline silicon substrate 10 is reduced. The side surface of the monocrystalline silicon substrate 10 is covered by the first intrinsic side edge part 210 and the second intrinsic side edge part 220, so that the passivation effect of the side surface of the monocrystalline silicon substrate 10 can be effectively improved, and the heterojunction solar cell has higher photoelectric conversion efficiency compared with a cell slice with an unpassivated edge in the prior art.

In the embodiment of the present invention, the doped side portions of the first doped amorphous layer 31 and the second doped amorphous layer 32 may have portions directly attached to the outer surface of the second intrinsic side portion 220 to form a connection therebetween; preferably, however, the doped side edge portion of the first doped amorphous layer 31 and the doped side edge portion of the second doped amorphous layer 32 are stacked over the second intrinsic side edge portion 220 to form a connection.

Referring to the embodiment shown in fig. 2, the first doped amorphous layer 31 has a region corresponding to a side surface overlying the second intrinsic side edge portion 220 in addition to a region corresponding to the first main surface overlying the first intrinsic amorphous layer 21, i.e., the first doped amorphous layer 31 has a first doped side edge portion 310 overlying an outer surface of the second intrinsic side edge portion 220.

As further shown in fig. 2, the second doped amorphous layer 32 has a region overlying the first doped side edge portion 310 in addition to a region overlying the second intrinsic amorphous layer 22 corresponding to the second major surface, i.e., the second doped amorphous layer 32 has a second doped side edge portion 320 overlying the outer surface of the second intrinsic side edge portion 220. In this embodiment, the first doped side portion 310 and the second doped side portion 320 are sequentially stacked outside the second intrinsic side portion 220.

In another embodiment of the present invention, referring to fig. 8, unlike the embodiment shown in fig. 2, the second doped side portion 320 covers the outer surface of the second intrinsic side portion 220, and the first doped side portion 310 covers the outer surface of the second doped side portion 320, i.e., the second doped side portion 320 and the first doped side portion 310 are sequentially stacked outside the second intrinsic side portion 220.

In other embodiments of the present invention (not shown), the first doped side portion 310 and the second doped side portion 320 may be formed directly on the outer surface of the second intrinsic side portion 220 and connected to each other by edges.

In the present invention, the doping type of the second doped amorphous layer 32 is opposite to the doping type of the first doped amorphous layer 31. In the specific implementation process, the first doped amorphous layer 31 is one of an N-type doped amorphous layer and a P-type doped amorphous layer, and the second doped amorphous layer 32 is the other of the N-type doped amorphous layer and the P-type doped amorphous layer. Specifically, the N-type doped amorphous layer is doped with phosphorus, and the P-type doped amorphous layer is doped with boron.

Further, the first transparent conductive film layer 41 according to the present invention is located on a surface of the first doped amorphous layer 31 facing away from the first intrinsic amorphous layer 21; the first collector electrode 51 is positioned on the surface of the first transparent conductive film layer 41 on the side away from the first doped amorphous layer 31; a second transparent conductive film layer 42 is disposed on a surface of the second doped amorphous layer 32 facing away from the second intrinsic amorphous layer 22; the second collector electrode 52 is located on a side surface of the second transparent conductive film layer 42 facing away from the second doped amorphous layer 32.

In the embodiment of the present invention shown in fig. 2 and 8, the first main surface is a light receiving surface, and the second main surface is a backlight surface. However, in another embodiment of the present invention, as shown in fig. 9 and 10, unlike the embodiment shown in fig. 2 and 8, the second main surface in both embodiments is a light receiving surface and the first main surface is a backlight surface.

In the present invention, the sum of the thicknesses of the first intrinsic amorphous layer 21, the first doped amorphous layer 31, the second intrinsic amorphous layer 22, and the second doped amorphous layer 32 on the light receiving surface is less than or equal to the sum of the thicknesses of the two layers on the back surface. Preferably, the sum of the thicknesses of the first intrinsic amorphous layer 21, the first doped amorphous layer 31, the second intrinsic amorphous layer 22, and the second doped amorphous layer 32 on the light receiving surface is smaller than the sum of the thicknesses of the two layers on the backlight surface.

For the heterojunction solar cell, the influence of the light absorption effect of the light receiving surface on the photoelectric conversion efficiency of the cell is far larger than the influence of the light absorption effect of the back surface on the photoelectric conversion efficiency of the cell, and as the sum of the thicknesses of the first intrinsic amorphous layer 21, the first doped amorphous layer 31, the second intrinsic amorphous layer 22 and the second doped amorphous layer 32 on the light receiving surface is smaller than or equal to the sum of the thicknesses of the two on the back surface, the loss of sunlight on the light receiving surface can be effectively reduced, the short-circuit current of the heterojunction solar cell can be improved, and the heterojunction solar cell has better photoelectric conversion efficiency.

For the structure shown in fig. 2 and 8, two of the first intrinsic amorphous layer 21, the first doped amorphous layer 31, the second intrinsic amorphous layer 22 and the second doped amorphous layer 32 on the light receiving surface are the first intrinsic amorphous layer 21 and the first doped amorphous layer 31, and two of the first intrinsic amorphous layer 21 and the second doped amorphous layer 32 on the backlight surface are the second intrinsic amorphous layer 22 and the second doped amorphous layer 32, wherein the sum of the thicknesses of the first intrinsic amorphous layer 21 and the first doped amorphous layer 31 is less than or equal to the sum of the thicknesses of the second intrinsic amorphous layer 22 and the second doped amorphous layer 32.

More specifically, in the embodiments shown in FIGS. 2 and 8, the sum of the thicknesses of the first intrinsic amorphous layer 21 and the first doped amorphous layer 31 is 6 to 21nm, and the sum of the thicknesses of the second intrinsic amorphous layer 22 and the second doped amorphous layer 32 is 6 to 30 nm.

In the structure shown in fig. 2 and 8, the thickness of the first intrinsic amorphous layer 21 is less than or equal to the thickness of the second intrinsic amorphous layer 22. It is preferable that the thickness of the first intrinsic amorphous layer 21 is smaller than that of the second intrinsic amorphous layer 22. In a specific embodiment, the first intrinsic amorphous layer 21 has a thickness of 3 to 6nm, and the second intrinsic amorphous layer 22 has a thickness of 3 to 10 nm.

Further, the thickness of the first doped amorphous layer 31 is less than or equal to the thickness of the second doped amorphous layer 32. It is preferable that the thickness of the first doped amorphous layer 31 is smaller than that of the second doped amorphous layer 32. In specific implementation, the thickness of the first doped amorphous layer 31 is 3-15nm, and the thickness of the second doped amorphous layer 32 is 3-20 nm.

In the present invention, in order to ensure a superior passivation effect of the side surface of the single crystal silicon substrate 10, in a specific implementation, the sum of the thicknesses of the first intrinsic side portion 21 and the portion of the second intrinsic side portion 22 covering the first intrinsic side portion 21 is not less than 1nm, and the thickness of the portion of the second intrinsic side portion 22 covering the side surface connected to the second main surface is not less than 1 nm.

In the structure shown in fig. 2 and 8, the oxygen content in the first doped amorphous layer 31 is greater than or equal to the oxygen content in the second doped amorphous layer 32. Generally, the high oxygen content in the first doped amorphous layer 31 forms amorphous silicon oxide with high light transmittance, thereby improving the light receiving effect of the light receiving surface of the heterojunction solar cell.

As a further specific embodiment of the structure shown in fig. 2 and 8, referring to fig. 3, the first doped amorphous layer 31 includes a first doped amorphous silicon film 301 on the surface of the first intrinsic amorphous layer 21 and a doped amorphous silicon oxide film, a doped amorphous silicon carbide film or a doped amorphous silicon carbide/doped amorphous silicon oxide composite film 302 on the surface of the first doped amorphous silicon film 301. It is easy to understand that the doped amorphous silicon carbide/doped amorphous silicon oxide composite film refers to a film layer formed by compounding a doped amorphous silicon oxide film and a doped amorphous silicon carbide film.

The doped amorphous silicon oxide and the doped amorphous silicon carbide have more excellent light transmittance compared with the doped amorphous silicon. The first doped amorphous layer 31' of the related art is generally a single-layer doped amorphous silicon film structure; in this embodiment, the first doped amorphous layer 31 is designed as a double-layer film, wherein the first doped amorphous silicon film 301 can ensure that the first doped amorphous layer 31 and the first intrinsic amorphous layer 21 have a good contact, and the doped amorphous silicon oxide film, the doped amorphous silicon carbide film or the doped amorphous silicon carbide/doped amorphous silicon oxide composite film 302 is equivalent to replacing a part of doped amorphous silicon in the prior art with doped amorphous silicon oxide or doped amorphous silicon carbide with high transmittance, so that the overall transmittance of the first doped amorphous layer 31 can be improved. Based on the cooperation of the first doped amorphous silicon film 301 and the doped amorphous silicon oxide film, the doped amorphous silicon carbide film or the doped amorphous silicon carbide/doped amorphous silicon oxide composite film 302, the heterojunction solar cell has more excellent performance.

In the embodiment illustrated in fig. 3, the thickness of the first doped amorphous silicon film 301 is preferably generally less than the thickness of the doped amorphous silicon oxide film, the doped amorphous silicon carbide film, or the doped amorphous silicon carbide/doped amorphous silicon oxide composite film 302. Thus, while ensuring a good contact between the first doped amorphous layer 31 and the first intrinsic amorphous layer 21, the first doped amorphous layer 31 can have a good transmittance to a great extent.

In the specific implementation process, the thickness of the doped amorphous silicon oxide film, the doped amorphous silicon carbide film or the doped amorphous silicon carbide/doped amorphous silicon oxide composite film 302 is 2-10 nm. Accordingly, the thickness of the first doped amorphous silicon film 301 is 1 to 5 nm.

To ensure a better contact between the first doped amorphous layer 31 and the first intrinsic amorphous layer 21, the first doped amorphous silicon film 301 is a highly doped film with a carrier concentration of 5E 19-5E 21/cm³。

In other embodiments of the structure of fig. 2 and 8, as shown in fig. 4, the first doped amorphous layer 31 further includes a second doped amorphous silicon film 303 on the surface of the doped amorphous silicon oxide film, the doped amorphous silicon carbide film, or the doped amorphous silicon carbide/doped amorphous silicon oxide composite film 302. The doped amorphous silicon generally has excellent conductivity, and the second doped amorphous silicon film 303 in the embodiment shown in fig. 4 is disposed to make the first doped amorphous layer 31 and the first transparent conductive film 41 have better contact, so that the contact resistance can be reduced compared to the embodiment shown in fig. 3, and thus the heterojunction solar cell has a higher fill factor.

In the embodiment shown in fig. 4, the thickness of the second doped amorphous silicon film 303 is also generally smaller than the thickness of the doped amorphous silicon oxide film, the doped amorphous silicon carbide film or the doped amorphous silicon carbide/doped amorphous silicon oxide composite film 302, so that the first doped amorphous layer 31 has better light transmittance. In specific implementation, the thickness of the first doped amorphous silicon film 301 is 1-4nm, the thickness of the doped amorphous silicon oxide film, the doped amorphous silicon carbide film or the doped amorphous silicon carbide/doped amorphous silicon oxide composite film 302 is 1-7nm, and the thickness of the second doped amorphous silicon film 303 is 1-4 nm.

In order to ensure a better contact between the first doped amorphous layer 31 and the first transparent conductive film 41, the second doped amorphous silicon film 303 is also a highly doped film with a carrier concentration of 5E 19-5E 21/cm³。

Referring to fig. 3 and 4, in still other embodiments of the present invention, the second doped amorphous layer 32 includes a third doped amorphous silicon film 304 on the surface of the second intrinsic amorphous layer 22 and a fourth doped amorphous silicon film 305 on the surface of the third doped amorphous silicon film 304 and having a doping concentration greater than that of the third doped amorphous silicon film 304.

Preferably, the carrier concentration of the third doped amorphous silicon film 304 is 5E 18-5E 19/cm³The carrier concentration of the fourth doped amorphous silicon film 305 is 5E 19-5E 21/cm³。

In the embodiment shown in fig. 3 and 4, the third doped amorphous silicon film 304 has a relatively low doping concentration, so that the influence on the second intrinsic amorphous layer 22 can be reduced, the lattice distortion of the second intrinsic amorphous layer 22 can be reduced, and the passivation effect of the backlight surface of the heterojunction solar cell can be effectively ensured; the fourth doped amorphous silicon film 305 has a relatively high doping concentration, so that the contact between the second doped amorphous layer 32 and the second transparent conductive film can be improved, the contact resistance between the second doped amorphous layer and the second transparent conductive film can be reduced, and the cell fill factor can be improved.

Preferably, the thickness of the third doped amorphous silicon film 304 is generally smaller than that of the fourth doped amorphous silicon film 305. In specific implementation, the thickness of the third doped amorphous silicon film 304 is 1-5nm, and the thickness of the fourth doped amorphous silicon film 305 is 2-15 nm.

It should be understood that in the embodiments of the present invention shown in fig. 9 and 10, two of the first intrinsic amorphous layer 21, the first doped amorphous layer 31, the second intrinsic amorphous layer 22 and the second doped amorphous layer 32 on the light receiving surface are the second intrinsic amorphous layer 22 and the second doped amorphous layer 32, and two of the first intrinsic amorphous layer 21 and the first doped amorphous layer 31 on the back light surface are the second intrinsic amorphous layer 22 and the second doped amorphous layer 32, wherein the sum of the thicknesses of the second intrinsic amorphous layer 22 and the second doped amorphous layer 32 is less than or equal to the sum of the thicknesses of the first intrinsic amorphous layer 21 and the first doped amorphous layer 31.

More specifically, the first intrinsic amorphous layer 21 and the first doped amorphous layer 31 in the implementation structure shown in fig. 9 and 10 can be respectively referred to the design of the second intrinsic amorphous layer 22 and the second doped amorphous layer 32 in the implementation structure shown in fig. 2 and 8, and the second intrinsic amorphous layer 22 and the second doped amorphous layer 32 in the implementation structure shown in fig. 9 and 10 can be respectively referred to the design of the first intrinsic amorphous layer 21 and the first doped amorphous layer 31 in the implementation structure shown in fig. 2 and 8. Details are not described herein.

Preferably, the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 according to the present invention each include at least two intrinsic films stacked one on another, each intrinsic film being formed of one of intrinsic amorphous silicon, intrinsic amorphous silicon oxide, and intrinsic amorphous silicon carbide.

Referring to fig. 7, a specific embodiment of the structure of fig. 2 is shown, in which the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 include three intrinsic films stacked one on another. In a direction away from the single crystal silicon substrate 10, the first intrinsic amorphous layer 21 sequentially includes a first intrinsic film 201, a second intrinsic film 202, and a third intrinsic film 203, and the second intrinsic amorphous layer 22 sequentially includes a fourth intrinsic film 204, a fifth intrinsic film 205, and a sixth intrinsic film 206. It is understood that the number of layers of the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 is not limited to the three-layer structure in other embodiments of the present invention.

In the present invention, since the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 both include at least two intrinsic films stacked on each other, the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 having superior overall performance can be formed by controlling the characteristics of each film in the specific implementation process.

As a preferable aspect of the present invention, in the embodying, a layer of the intrinsic film of the first intrinsic amorphous layer 21 farthest from the single crystal silicon substrate 10 is provided as intrinsic amorphous silicon oxide. Referring to fig. 7, in this embodiment, the third intrinsic film 203 is an intrinsic film of the first intrinsic amorphous layer 21 farthest from the single crystal silicon substrate 10, and the third intrinsic film 203 in this embodiment preferably uses intrinsic amorphous silicon oxide. It is to be understood that in other embodiments of the present invention, the layer of the intrinsic film of the second intrinsic amorphous layer 22 farthest from the single crystal silicon substrate 10 may also be provided with intrinsic amorphous silicon oxide, i.e., the sixth intrinsic film 206 farthest from the single crystal silicon substrate 10 in this embodiment may be provided with intrinsic amorphous silicon oxide.

The intrinsic amorphous silicon oxide has a lower passivation effect than intrinsic amorphous silicon and intrinsic amorphous silicon carbide, but has a better light transmittance than intrinsic amorphous silicon and intrinsic amorphous silicon carbide, and in the heterojunction solar cell, an intrinsic film, which is the farthest layer from the monocrystalline silicon substrate 10, of the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 has a limited passivation effect on the monocrystalline silicon substrate 10 due to the distance, and the intrinsic amorphous silicon oxide with the optimal light transmittance can optimize the photoelectric conversion efficiency of the heterojunction solar cell to a certain extent.

As a further preferable aspect of the present invention, the hydrogen content of the intrinsic film near the single-crystal silicon substrate 10 in the first intrinsic amorphous layer 21 is higher than the hydrogen content of the intrinsic film far from the single-crystal silicon substrate, and the hydrogen content of the intrinsic film near the single-crystal silicon substrate 10 in the second intrinsic amorphous layer 22 is higher than the hydrogen content of the intrinsic film far from the single-crystal silicon substrate.

Referring to fig. 7, in this embodiment, the hydrogen contents of the first, second, and third

intrinsic films

201, 202, and 203 in the first intrinsic amorphous layer 21 are sequentially reduced, and the hydrogen contents of the fourth, fifth, and sixth

intrinsic films

204, 205, and 206 in the second intrinsic amorphous layer 22 are also sequentially reduced. It can be easily understood that the intrinsic films of the first and second intrinsic

amorphous layers

21 and 22 closer to the single crystal silicon substrate 10 have more significant passivation effect, and the first and fourth intrinsic films 201 and 204 are directly attached to the single crystal silicon substrate 10, and have the highest hydrogen content such that the first and second intrinsic

amorphous layers

21 and 22 have the optimal passivation effect on the single crystal silicon substrate 10.

As a preferable aspect of the present invention, when the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 include three intrinsic films stacked one on another, the hydrogen content of the three intrinsic films of the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 ranges from 20% to 40%, from 10% to 25%, and from 8% to 20% in this order in a direction away from the single crystal silicon substrate 10. That is, the hydrogen content of the first and fourth intrinsic films 201 and 204 ranges from 20% to 40%, the hydrogen content of the second and fifth

intrinsic films

202 and 205 ranges from 10% to 25%, and the hydrogen content of the third and sixth

intrinsic films

203 and 206 ranges from 8% to 20%.

Further preferably, in the embodiment shown in fig. 7, the hydrogen content of the first intrinsic film 201 and the fourth intrinsic film 204 ranges from 24% to 30%, the hydrogen content of the second intrinsic film 202 and the fifth intrinsic film 205 ranges from 12% to 18%, and the hydrogen content of the third intrinsic film 203 and the sixth intrinsic film 206 ranges from 10% to 15%.

As a further preferable embodiment of the present invention shown in fig. 7, when the first main surface of the single crystal silicon substrate 10 is a light receiving surface, the first intrinsic film 201, the second intrinsic film 202 and the third intrinsic film 203 in the first intrinsic amorphous layer 21 have thicknesses of 1 to 3nm, 2 to 4nm and 1 to 3nm in this order, and the fourth intrinsic film 204, the fifth intrinsic film 205 and the sixth intrinsic film 206 in the second intrinsic amorphous layer 22 have thicknesses of 1 to 5nm, 3 to 10nm and 0 to 5nm in this order.

Accordingly, it can be understood that when the first main surface of the single crystal silicon substrate 10 is a back light surface, the thicknesses of the fourth intrinsic film 204, the fifth intrinsic film 205, and the sixth intrinsic film 206 in the second intrinsic amorphous layer 22 are in the order of 1-3nm, 2-4nm, and 1-3nm, and the thicknesses of the first intrinsic film 201, the second intrinsic film 202, and the third intrinsic film 203 in the first intrinsic amorphous layer 21 are in the order of 1-5nm, 3-10nm, and 0-5 nm.

It is further preferable that the ratio of bonded hydrogen atoms in the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 referred to in the present invention is 15% to 25% of the total hydrogen atoms. During the specific passivation, the bonded hydrogen atoms play a decisive role, the bonded hydrogen atoms in the amorphous layer of the intrinsic layer in the prior art account for about 10% of the total hydrogen atoms, and the passivation effect of the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 on the surface of the monocrystalline silicon substrate 10 can also be improved by improving the ratio of the bonded hydrogen atoms in the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 to the total hydrogen atoms, so that the open-circuit voltage of the corresponding heterojunction solar cell is further improved.

In other embodiments of the present invention, the average concentration of hydrogen atoms in the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 is 1e22-5e22/cm³(ii) a Preferably 2.5e22-5e22/cm³. The concentration of hydrogen atoms in the intrinsic layer amorphous silicon layer of the heterojunction solar cells of the prior art is generally less than 1e22 atoms/cm³The low concentration of hydrogen atom content makes the intrinsic layer amorphous silicon layer have a poor passivation effect. According to the invention, by increasing the hydrogen atom concentration in the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22, the passivation effect of the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 on the surface of the monocrystalline silicon substrate 10 can be effectively improved, and further the open-circuit voltage of the corresponding heterojunction solar cell is improved.

Although the single crystal silicon substrate 10 may specifically be a p-type single crystal silicon substrate, an n-type single crystal substrate silicon may also be selected; however, in a preferred embodiment of the present invention, the single crystal silicon substrate 10 is an n-type single crystal silicon substrate. Further preferably, the first doped amorphous layer 31 and the second doped amorphous layer 32 on the light receiving surface side are n-type doped amorphous layers, and the first doped amorphous layer 31 and the second doped amorphous layer 32 on the backlight surface side are p-type doped amorphous layers.

When the first doped amorphous layer 31 and the second doped amorphous layer 32 located on the light receiving surface side are n-type doped amorphous layers, and the first doped amorphous layer 31 and the second doped amorphous layer 32 located on the backlight surface side are p-type doped amorphous layers, the first transparent conductive film 41 and the second transparent conductive film 42 according to the present invention have the following design.

For the embodiments shown in fig. 2 and 8, one embodiment of which is shown in fig. 5, the first transparent conductive film layer 41 includes a first TCO film 401 attached to the surface of the n-type doped amorphous layer (first doped amorphous layer 31) and a second TCO film 402 attached to the surface of the first TCO film 401, wherein the mass fraction of doped oxide in the first TCO film 401 is greater than the mass fraction of doped oxide in the second TCO film 402.

In the heterojunction solar cell structure provided by the embodiment, based on the specific design structure, the first TCO film 401 can ensure that the first transparent conductive film layer 41 and the n-type doped amorphous layer (first doped amorphous layer 31) have better contact due to high doping, so that the contact resistance is reduced, and the fill factor of the heterojunction solar cell can be improved; the light transmittance of the first transparent conductive film layer 41 can be increased on the whole due to the low doping of the second TCO film 402, so that the short-circuit current of the heterojunction solar cell can be increased.

Preferably, in the specific implementation process of the structure, the mass ratio of the doped oxide in the first TCO film 401 is 5% to 20%, and the mass ratio of the doped oxide in the second TCO film 402 is 0.5% to 5%.

Further, the carrier concentration of the first TCO film 401 is 3e20-1e21/cm³The carrier concentration of the second TCO film 402 is 5e19-4e20/cm³. In the specific implementation process, the ratio of the carrier concentration in the first TCO film 401 and the second TCO film 402 to the mass of the doped oxide in the corresponding film layers is in a positive phaseIn this regard, in a specific manufacturing process, the carrier concentration can be further adjusted to some extent by controlling the film formation atmosphere (for example, adjusting the oxygen concentration) of the first TCO film 401 and the second TCO film 402.

As a preferable structure of this embodiment, the thickness of the first TCO film 401 is smaller than that of the second TCO film 402. More specifically, referring to FIG. 5, the first TCO film 401 has a thickness of 5-15nm, with 5-10nm being preferred; the thickness of the second TCO film 402 is 40-90nm, with 60-80nm being most preferred.

The first TCO film 401 is mainly disposed to form a better contact between the first transparent conductive film 41 and the n-type doped amorphous layer (the first doped amorphous layer 31), and a relatively thin thickness can satisfy the requirement. The second TCO film 402 has a good light transmittance due to a low doping concentration, and when the first transparent conductive film layer 41 has a sufficient thickness, the second TCO film 402 is set to have a relatively thick thickness, so that the first transparent conductive film layer 41 can also ensure an excellent light transmittance, and further, the heterojunction solar cell has a high short-circuit current.

With further reference to fig. 6, in other embodiments of the invention, the first transparent conductive film layer 41 further includes a third TCO film 403 attached to the surface of the second TCO film 402, where the mass fraction of the doped oxide in the third TCO film 403 is greater than the mass fraction of the doped oxide in the second TCO film 402. In specific implementation, the mass ratio of the doped oxide in the third TCO film 403 is 5% to 20%.

Since the doping concentration of the third TCO film 403 has a relatively high value, it can ensure that the first transparent conductive film layer 41 and the first collector electrode 51 have a good contact therebetween, and can also reduce the contact resistance therebetween, thereby further improving the fill factor of the heterojunction solar cell.

In a specific implementation, the thickness of the third TCO film 403 is less than the thickness of the second TCO film 402. In the embodiment shown in FIG. 6, the first TCO film 401 has a thickness of 5-15nm, the second TCO film 402 has a thickness of 35-75nm, and the third TCO film 403 has a thickness of 5-15 nm. The consideration for setting the thickness of the third TCO film 403 to a relatively small value may refer to the consideration for setting the thickness of the first TCO film 401, and will not be further described here.

In the specific implementation process of the present embodiment, the first TCO film 401, the second TCO film 402, and the third TCO film 403 are all formed by doping doped oxide in indium oxide or zinc oxide, where the doped oxide is Al2O₃、Ga₂O₃、In₂O₃、SnO₂、WO₃、TiO₂、ZrO₂And MoO₂One or more of (a). Among them, the doped oxide is preferably SnO₂And the reliability is better. It is understood that the mass fraction of doped oxide in a respective TCO film refers to the ratio of the mass of doped oxide to the total mass of the respective TCO film.

Referring to fig. 5 and 6, in these embodiments, the second transparent conductive film layer 42 includes a fourth TCO film 404 attached to the surface of the p-type doped amorphous layer (the second doped amorphous layer 32) and a fifth TCO film 405 attached to the surface of the fourth TCO film 404, wherein the mass fraction of the doped oxide in the fourth TCO film 404 is smaller than the mass fraction of the doped oxide in the fifth TCO film 405.

Since the fourth TCO film 404 is in direct contact with the p-type doped amorphous layer (the second doped amorphous layer 32), when the fourth TCO film 404 has a lower concentration of doping, the schottky contact barrier between the two is reduced, so that the two can have an optimal contact, thereby increasing the fill factor of the heterojunction solar cell. In addition, the fifth TCO film 405 has a higher doping concentration, so that the fifth TCO film has a better conductivity, and has a better electrical contact with the second collector, so that the fill factor of the heterojunction solar cell can be improved. It can be known that, because the second transparent conductive film layer 42 is located the backlight surface of heterojunction solar cell, when specifically applying, shine to the inside sunlight proportion of heterojunction solar cell very low through second transparent conductive film layer 42, its luminousness is little to heterojunction solar cell's wholeness ability influence.

In a specific implementation process, the mass percentage of the doped oxide in the fourth TCO film 404 is 0.5% to 5%, and the mass percentage of the doped oxide in the fifth TCO film 405 is 5% to 20%.

Correspondingly, the carrier concentration of the fourth TCO film 404 is 5e19-4e20/cm³The carrier concentration of the fifth TCO film 405 is 3e20-1e21/cm³。

Preferably, in this embodiment, the thickness of the fourth TCO film 404 is generally smaller than the thickness of the fifth TCO film 405. The fourth TCO film 404 is set to a relatively small value so as to satisfy the excellent contact with the p-type doped amorphous layer (the second doped amorphous layer 32), and the fifth TCO film 405 is set to a relatively large value so as to satisfy the requirement of the total thickness of the second transparent conductive film 42 and improve the electrical properties of the second transparent conductive film 42.

In some embodiments, the fourth TCO film 404 has a thickness of 5-15nm and the fifth TCO film 405 has a thickness of 40-90 nm.

The fourth TCO film 404 and the fifth TCO film 405 in this embodiment are formed by doping the doped oxide with indium oxide or zinc oxide, where the doped oxide is Al2O₃、Ga2O₃、In₂O₃、SnO₂、WO₃、TiO₂、ZrO₂And MoO₂One or more of (a). Among them, SnO2 is preferable as the doped oxide, and the reliability is better.

In the present embodiment, the thickness of the first transparent conductive film layer 41 is less than or equal to the thickness of the second transparent conductive film layer 42. Among them, the thickness of the first transparent conductive film layer 41 is preferably smaller than the thickness of the second transparent conductive film layer 42. The total thickness of the first transparent conductive film layer 41 is 60-120nm, preferably 60-90 nm.

For the heterojunction solar cell, the influence of the light absorption effect of the light receiving surface on the photoelectric conversion efficiency of the cell is far larger than the influence of the light absorption effect of the backlight surface on the photoelectric conversion efficiency of the cell, and the loss of sunlight on the light receiving surface when the sunlight passes through the first transparent conductive film layer 41 can be effectively reduced due to the small thickness of the first transparent conductive film layer 41, so that the heterojunction solar cell has better photoelectric conversion efficiency.

It is understood that in other embodiments of the present embodiment structure, the second transparent conductive film layer 42 may be a single-layer structure, that is, only the first transparent conductive film layer 41 may be a double-layer film or a three-layer film structure.

It should be understood that in the implementation structures shown in fig. 9 and 10 of the present invention, one of the first transparent conductive film layer 41 and the second transparent conductive film layer 42 located on the light receiving surface is the second transparent conductive film layer 42, and the other one located on the backlight surface is the first transparent conductive film layer 41. At this time, the design of the second transparent conductive film layer 42 in the implementation structure shown in fig. 2 and 8 can be referred to for the first transparent conductive film layer 41 in the implementation structure shown in fig. 9 and 10, and the design of the first transparent conductive film layer 41 in the implementation structure shown in fig. 2 and 8 can be referred to for the second transparent conductive film layer 42 in the implementation structure shown in fig. 9 and 10. Details are not described herein.

Further, in the present invention, one of the first transparent conductive film layer 41 and the second transparent conductive film layer 42 extends out of the side surface to cover the doped side edge portion. Therefore, the current collection can be carried out on the surface of the heterojunction solar cell more comprehensively, and the photoelectric conversion efficiency of the cell piece is improved. More specific reference may be made to the following different embodiments.

Referring to fig. 2, in an embodiment, first transparent conductive film layer 41 has a first conductive layer side portion 410 that extends out of the side surface to cover second doped side portion 320. At this time, the second transparent conductive film layer 42 covers only the region of the second doped amorphous layer 32 corresponding to the second main surface, and a blank region insulated from the side edge portion 410 of the first conductive layer is formed around the second doped amorphous layer.

Referring to fig. 8, in this embodiment, the first transparent conductive film layer 41 has a first conductive layer side edge portion 410 extending out of the side surface to cover the first doped side edge portion 310. At this time, the second transparent conductive film layer 42 covers only the region of the second doped amorphous layer 32 corresponding to the second main surface, and a blank region insulated from the side edge portion 410 of the first conductive layer is formed around the second doped amorphous layer.

Referring to fig. 9, in this embodiment, second transparent conductive film layer 42 has a second conductive layer side portion 420 that extends out of the side to cover first doped side portion 310. At this time, the first transparent conductive film layer 41 covers only the region of the first doped amorphous layer 31 corresponding to the first main surface, and a blank region insulated from the side edge portion 420 of the second conductive layer is formed around the first transparent conductive film layer.

Referring to fig. 10, in this embodiment, second transparent conductive film layer 42 has a second conductive layer side portion 420 that extends out of the side to cover second doped side portion 320. At this time, the first transparent conductive film layer 41 covers only the region of the first doped amorphous layer 31 corresponding to the first main surface, and a blank region insulated from the side edge portion 420 of the second conductive layer is formed around the first transparent conductive film layer.

Referring to fig. 11, in this embodiment, second transparent conductive film layer 42 has a second conductive layer side portion 420 that extends out of the side to cover second doped side portion 320. At this time, the first transparent conductive film layer 41 covers only the region of the first doped amorphous layer 31 corresponding to the first main surface, and a blank region insulated from the side edge portion 420 of the second conductive layer is formed around the first transparent conductive film layer.

In comparison with the above embodiments, in the embodiments shown in fig. 2, 8, 9 and 10, one of the first transparent conductive film layer 41 and the second transparent conductive film layer 42 on the light receiving surface side extends to the outside of the side surface to cover the doped side edge portion. In the embodiment shown in fig. 11, one of the first transparent conductive film layer 41 and the second transparent conductive film layer 42 on the backlight side extends out of the side surface to cover the doped side edge portion, and other similar implementation structures are not further developed herein.

In a specific implementation process, a width of a blank region between the first transparent conductive film layer 41 and the second transparent conductive film layer 42 for insulating the two layers is in a range of 0.5-2 mm.

The invention also provides a method for manufacturing a heterojunction solar cell, which is used for manufacturing the heterojunction solar cell and comprises the following steps:

and a monocrystalline silicon substrate texturing step of texturing the first main surface, the second main surface and the side surfaces of the monocrystalline silicon substrate 10.

Referring to fig. 12, a first intrinsic amorphous layer manufacturing step, referring to fig. 12, places the single crystal silicon substrate 10 on the first carrier 61 with the first main surface facing upward, the first carrier 61 has a first groove 610 for placing the single crystal silicon substrate 10, the first intrinsic amorphous layer 21 is formed by deposition on the first main surface side of the single crystal silicon substrate 10 from the upper side of the first carrier 61, the periphery of the first intrinsic amorphous layer 21 extends to cover all sides, and in practical implementation, the portion of the first intrinsic amorphous layer 21 extending to cover all sides constitutes the first intrinsic side portion 210.

A second intrinsic amorphous layer manufacturing step, referring to fig. 13, the single crystal silicon substrate 10 after the first intrinsic amorphous layer manufacturing step is placed on the second carrier 62 with the second main surface facing upward, the second carrier 62 has a second recess 620 for placing the single crystal silicon substrate 10, the second intrinsic amorphous layer 22 is formed by deposition on the second main surface side of the single crystal silicon substrate 10 from the upper side of the second carrier 62, the periphery of the second intrinsic amorphous layer 22 extends to cover the first intrinsic side portion 210, and the portion of the periphery of the second intrinsic amorphous layer 22 covering the first intrinsic side portion 210 constitutes the second intrinsic side portion 220.

A first doped amorphous layer manufacturing step, referring to fig. 14, the monocrystalline silicon substrate 10 after the second intrinsic amorphous layer manufacturing step is placed on a third carrier 63 with the first main surface facing upward, the third carrier 63 has a third groove 630 for placing the monocrystalline silicon substrate 10, a first doped amorphous layer 31 is formed on the first intrinsic amorphous layer 21 from the upper side of the third carrier 63, and the first doped amorphous layer 31 is formed with a first doped side portion 310 extending to the outside of the side surface.

A second doped amorphous layer manufacturing step, referring to fig. 15, the monocrystalline silicon substrate 10 after the second intrinsic amorphous layer manufacturing step is placed on a fourth carrier 64 with the second main surface facing upward, the fourth carrier 64 has a fourth groove 640 for placing the monocrystalline silicon substrate 10, the first doped amorphous layer 32 is formed on the second intrinsic amorphous layer 22 from the upper side of the fourth carrier 640, and the second doped amorphous layer 32 is formed with a second doped side portion 320 extending out of the side surface and forming a connection with the first doped side portion 310.

And a transparent conductive film layer manufacturing step, in which the transparent conductive film layer includes a first transparent conductive film layer 41 and a second transparent conductive film layer 42, and the first main surface side and the second main surface side of the monocrystalline silicon substrate 10 after the first doped amorphous layer manufacturing step and the second doped amorphous layer manufacturing step are deposited respectively to form the first transparent conductive film layer 41 and the second transparent conductive film layer 42.

And a collector manufacturing step, wherein the collector comprises a first collector 51 and a second collector 52, the first collector 51 is formed on the surface of the first transparent conductive film layer 41, which is far away from the first doped amorphous layer 31, and the second collector 52 is formed on the surface of the second transparent conductive film layer 42, which is far away from the second doped amorphous layer 32.

In the specific implementation process of the present invention, the order of the second doped amorphous layer and the first doped amorphous layer is adjustable. Heterojunction solar cells can be formed in which the first doped side portion 310 and the second doped side portion 320 are arranged in a different order.

In the embodiment of the present invention, when the second doped amorphous layer manufacturing step is located before the first doped amorphous layer manufacturing step, the second carrier 62 involved in the second intrinsic amorphous layer manufacturing step and the fourth carrier 64 involved in the second doped amorphous layer manufacturing step can be the same carrier, and the monocrystalline silicon substrate 10 does not need to be moved during the execution of the two steps.

In a specific transparent conductive film layer manufacturing step, referring to fig. 16, the monocrystalline silicon substrate 10 having the second amorphous film manufacturing step is placed on a fifth carrier 70 with the first main surface facing upward, the fifth carrier 70 includes a through hole 700 penetrating from top to bottom, a carrying portion 701 for carrying the monocrystalline silicon substrate 10 and shielding a side edge of the second main surface of the monocrystalline silicon substrate 10 is disposed in the through hole 700, a size of an upper side region of the through hole 700 on the carrying portion 701 is larger than a size of the monocrystalline silicon substrate 10, and a difference typically ranges from 2mm to 4 mm. The first transparent conductive film layer 41 and the second transparent conductive film layer 42 are respectively formed on one side of the first main surface and one side of the second main surface by depositing the fifth carrier 70, so that the heterojunction solar cell with the structure shown in fig. 2 and 8 can be formed.

In this embodiment, since the size of the through hole 700 at the upper side of the supporting portion 701 is larger than the size of the single crystal silicon substrate 10, the first transparent conductive film layer 41 will extend to the side of the single crystal silicon substrate 10 during the formation process to form the side portion 410 of the first conductive layer, and a blank area is formed at the portion of the side edge of the second main surface of the single crystal silicon substrate 10, which is shielded by the supporting portion 701.

In another embodiment of the present invention, the single-crystal silicon substrate 10 having the second amorphous film forming step completed thereon may also be placed on a fifth carrier 70 (not shown), wherein the second main surface of the single-crystal silicon substrate faces upward, so that the heterojunction solar cell having the structure shown in fig. 9, 10 or 11 can be formed, which will not be further described herein.

In order to form the second intrinsic side portion 220, the first doped side portion 310 and the second doped side portion 320 on the side surface of the single crystal silicon substrate 10, in the implementation process of the present invention, the difference between the side length of the first groove 610, the second groove 620, the third groove 630 and the fourth groove 640 and the corresponding side length of the single crystal silicon substrate 10 is 2-4 mm. Based on the difference between the side length of the first groove 610, the second groove 620, the third groove 630 and the fourth groove 640 and the corresponding side length of the monocrystalline silicon substrate 10, when the corresponding film layer is manufactured, a gap of 1-2mm can be formed between each side edge of the monocrystalline silicon substrate 10 and the corresponding groove edge, so that the corresponding film layer can be fully wound and plated on the side edge of the monocrystalline silicon substrate 10.

In the invention, in the step of texturing the monocrystalline silicon substrate, firstly, an HF solution with the dilution solubility of 5% is used for removing a surface oxide layer, and then, by utilizing the anisotropic corrosion characteristic of the monocrystalline silicon, a solution of KOH or NaOH or tetramethyl ammonium hydroxide (TMAH) added with alcohol is used for texturing.

The four amorphous layers of the first intrinsic amorphous layer 21, the second intrinsic amorphous layer 22, the first doped amorphous layer 31 and the second doped amorphous layer 32 are formed by PECVD deposition process. The first transparent conductive film layer 41 and the second transparent conductive film layer 42 involved in the invention are formed by PVD deposition, RPD deposition or magnetron sputtering deposition. The first and second

current collectors

51 and 52 according to the present invention are formed by a screen printing process.

For better understanding of the present invention, a specific manufacturing method of the four amorphous layers of the heterojunction solar cell is also shown below: pure SiH is firstly introduced towards one side of the first main surface of the monocrystalline silicon substrate 10₄Then is introduced into the reaction vessel via H₂Dilute SiH₄Growing under the action of a 13.56MHz radio frequency power supplyAn intrinsic amorphous layer 21; pure SiH is firstly introduced towards one side of the second main surface of the monocrystalline silicon substrate 10₄Then is introduced into the reaction vessel via H₂Dilute SiH₄Growing a second intrinsic amorphous layer 22 under the action of a radio frequency power supply of 13.56 MHz; PH is introduced to the side of the first main surface of the single crystal silicon substrate 10₃、SiH₄、H₂Making a first doped amorphous layer 31 by gas and gas; b is introduced into the second main surface of the single-crystal silicon substrate 10₂H₆、SiH₄、H₂And the gases are mixed to form the second doped amorphous layer 32.

It is to be understood that the first intrinsic amorphous layer 21, the first doped amorphous layer 31, the second intrinsic amorphous layer 22 and the second doped amorphous layer 32 are formed in different coating chambers, respectively. In addition, in the four-layer amorphous layer plating process, before the corresponding amorphous layer is plated, the temperature and the pressure of the related plating chamber need to reach preset values, the temperature is usually 180 ℃, and the pressure is controlled to be 30-200 pa.

In order to optimize the passivation effect of the first and second intrinsic

amorphous layers

21 and 22 on the single crystal silicon substrate 10, in the specific manufacturing process of the first and second intrinsic

amorphous layers

21 and 22, when SiH4 diluted with H2 is introduced, the dilution ratio of H2/SiH4 may be adjusted, so that the first and second intrinsic

amorphous layers

21 and 22 have multiple intrinsic films with different characteristics, and the dilution ratio of H2/SiH4 is usually in the range of 5-250.

While only the first and second intrinsic

amorphous layers

21 and 22 are formed of intrinsic amorphous silicon, it is understood that the intrinsic films of the first and second intrinsic

amorphous layers

21 and 22 may be intrinsic amorphous silicon oxide or intrinsic amorphous silicon carbide in other embodiments of the present invention. And in particular will not be described further herein.

When the first doped amorphous layer 31 and the second doped amorphous layer 32 are fabricated, CO can be introduced into the corresponding coating chamber₂Or CH₄Further, the first doped amorphous layer 31 and the second doped amorphous layer 32 are made of amorphous silicon oxide or amorphous silicon carbide. More specifically, reference is made to the following.

In the manufacture of the first dopingIn the case of the amorphous film 301, SiH is added₄、H₂And a first type of dopant gas is introduced into the vacuum chamber.

When the doped amorphous silicon oxide film, the doped amorphous silicon carbide film or the doped amorphous silicon carbide/doped amorphous silicon oxide composite film 302 is manufactured: if the film is a doped amorphous silicon oxide film, SiH is added₄、H₂、CO₂And a first type of dopant gas is introduced into the vacuum chamber; if the film is a doped amorphous silicon carbide film, SiH is added₄、H₂、CH₄And a first type of dopant gas is introduced into the vacuum chamber; if the film layer is a doped amorphous silicon carbide/doped amorphous silicon oxide composite film, SiH is added₄、H₂、CO₂、CH₄And introducing the first type of doped gas into the vacuum chamber simultaneously to form a composite film, or separately depositing at least one layer of doped amorphous silicon oxide and at least one layer of doped amorphous silicon carbide to form the composite film. In the invention, the doped amorphous silicon oxide film, the doped amorphous silicon carbide film or the doped amorphous silicon carbide/doped amorphous silicon oxide composite film 302 can increase the optical band gap of the light receiving surface film layer of the heterojunction solar cell, increase the light transmission and improve the optical performance of the cell.

When the second doped amorphous film 303 needs to be formed, SiH is added₄、H₂And a first type of dopant gas is introduced into the vacuum chamber.

During the fabrication of the third doped amorphous film 304 and the fourth doped amorphous film 305, SiH is added₄、H₂And a second type dopant gas is introduced into the vacuum chamber. The difference is that the doping concentration of the second type dopant gas when the third doped amorphous film 303 is formed is smaller than that when the fourth doped amorphous film 304 is formed.

It should be understood that the above reference to the first type of dopant gas is to PH₃(Hydrogen phosphide) gas and B₂H₆One of the (diborane) gases, the second type dopant gas being PH₃(Hydrogen phosphide) gas and B₂H₆The other of (diborane) gases.

It should be understood that although the present description refers to embodiments, not every embodiment contains only a single technical solution, and such description is for clarity only, and those skilled in the art should make the description as a whole, and the technical solutions in the embodiments can also be combined appropriately to form other embodiments understood by those skilled in the art.

The above-listed detailed description is only a specific description of a possible embodiment of the present invention, and they are not intended to limit the scope of the present invention, and equivalent embodiments or modifications made without departing from the technical spirit of the present invention should be included in the scope of the present invention.

Claims

1. A heterojunction solar cell comprises a monocrystalline silicon substrate, wherein the monocrystalline silicon substrate is provided with a first main surface and a second main surface which are arranged in an opposite way, and a side surface connecting the first main surface and the second main surface, one of the first main surface and the second main surface is a light receiving surface, and the other one of the first main surface and the second main surface is a backlight surface; the heterojunction solar cell is characterized by further comprising a first intrinsic amorphous layer, a first doped amorphous layer, a first transparent conductive film layer and a first collector which are sequentially arranged on one side of the first main surface, and a second intrinsic amorphous layer, a second doped amorphous layer, a second transparent conductive film layer and a second collector which are sequentially arranged on one side of the second main surface, wherein the first intrinsic amorphous layer is provided with a first intrinsic side edge portion which extends towards the direction of the second intrinsic amorphous layer to cover the whole side surface, the second intrinsic amorphous layer is provided with a second intrinsic side edge portion which extends towards the direction of the first intrinsic amorphous layer to cover the first intrinsic side edge portion, and the first doped amorphous layer and the second doped amorphous layer are opposite in doping type and are provided with doped side edge portions which extend out of the side surface and are mutually connected.

2. The heterojunction solar cell of claim 1, wherein the sum of the thicknesses of the first intrinsic amorphous layer, the first doped amorphous layer, the second intrinsic amorphous layer and the second doped amorphous layer on the light receiving surface is less than or equal to the sum of the thicknesses of the two layers on the backlight surface.

3. The heterojunction solar cell of claim 2, wherein the sum of the thicknesses of the first intrinsic amorphous layer, the first doped amorphous layer, the second intrinsic amorphous layer and the second doped amorphous layer on the light receiving surface is 6-21nm, and the sum of the thicknesses of the first intrinsic amorphous layer, the first doped amorphous layer, the second intrinsic amorphous layer and the second doped amorphous layer on the backlight surface is 6-30 nm.

4. The heterojunction solar cell of any of claims 1 to 3, wherein the thickness of the first intrinsic amorphous layer and the second intrinsic amorphous layer on the light receiving surface is less than or equal to the thickness on the backlight surface.

5. The heterojunction solar cell of claim 4, wherein the thickness of the first intrinsic amorphous layer and the second intrinsic amorphous layer on the light receiving surface is 3-6nm, and the thickness on the backlight surface is 3-10 nm.

6. The heterojunction solar cell of any of claims 1 to 3, wherein the thickness of the first doped amorphous layer and the second doped amorphous layer on the light receiving surface side is less than or equal to the thickness on the backlight surface side.

7. The heterojunction solar cell of claim 6, wherein the thickness of the first doped amorphous layer and the second doped amorphous layer on the light receiving surface side is 3-15nm, and the thickness of the first doped amorphous layer and the second doped amorphous layer on the backlight surface side is 3-20 nm.

8. The heterojunction solar cell of claim 1, wherein the oxygen content of the first doped amorphous layer and the second doped amorphous layer on the light receiving surface is greater than or equal to the oxygen content on the backlight surface side.

9. The heterojunction solar cell of claim 1, 2, 3 or 8, wherein the first doped amorphous layer and the second doped amorphous layer sequentially comprise a first doped amorphous silicon film and a doped amorphous silicon oxide film, a doped amorphous silicon carbide film or a doped amorphous silicon carbide/doped amorphous silicon oxide composite film on the surface of the first doped amorphous silicon film from the backlight surface to the light receiving surface.

10. The heterojunction solar cell of claim 9, wherein the first doped amorphous layer and the second doped amorphous layer on the light-receiving surface further comprise a second doped amorphous silicon film on the surface of the doped amorphous silicon oxide film, the doped amorphous silicon carbide film or the doped amorphous silicon carbide/doped amorphous silicon oxide composite film.

11. The heterojunction solar cell of claim 1, 2, 3 or 8, wherein the first doped amorphous layer and the second doped amorphous layer sequentially comprise a third doped amorphous silicon film and a fourth doped amorphous silicon film on the surface of the third doped amorphous silicon film and having a doping concentration greater than that of the third doped amorphous silicon film, from the light receiving surface to the backlight surface.

12. The heterojunction solar cell of claim 1, 2, 3 or 8, wherein the doped side edge portion of the first doped amorphous layer and the doped side edge portion of the second doped amorphous layer are stacked outside the second intrinsic side edge portion.

13. The heterojunction solar cell of claim 1, 2, 3 or 8, wherein the sum of the thicknesses of the portions of the first and second intrinsic side edge portions covering the first intrinsic side edge portion and the thickness of the portion of the second intrinsic side edge portion covering the side surface connected to the second main surface are not less than 1 nm.

14. The heterojunction solar cell of claim 1, 2, 3 or 8, wherein the first intrinsic amorphous layer and the second intrinsic amorphous layer respectively comprise at least two intrinsic films stacked one on another, each intrinsic film being formed of one of intrinsic amorphous silicon, intrinsic amorphous silicon oxide and intrinsic amorphous silicon carbide.

15. The heterojunction solar cell of claim 14, wherein the layer of intrinsic film of the first intrinsic amorphous layer and/or the second intrinsic amorphous layer furthest from the single crystal silicon substrate is intrinsic amorphous silicon oxide.

16. The heterojunction solar cell of claim 14, wherein the intrinsic film hydrogen content of the first intrinsic amorphous layer is higher near the monocrystalline silicon substrate than far from the monocrystalline silicon substrate, and wherein the intrinsic film hydrogen content of the second intrinsic amorphous layer is higher near the monocrystalline silicon substrate than far from the monocrystalline silicon substrate.

17. The heterojunction solar cell of claim 16, wherein the first intrinsic amorphous layer and the second intrinsic amorphous layer each comprise three intrinsic films stacked one on top of the other, and the hydrogen content of the three intrinsic films of the first intrinsic amorphous layer and the second intrinsic amorphous layer ranges from 20% to 40%, from 10% to 25%, and from 8% to 20% in sequence in a direction away from the single crystal silicon substrate.

18. The heterojunction solar cell of claim 1, 2, 3 or 8, wherein the single-crystal silicon substrate is n-type single-crystal silicon, the first doped amorphous layer and the second doped amorphous layer on the light receiving surface side are n-type doped amorphous layers, and the first doped amorphous layer and the second doped amorphous layer on the backlight surface side are p-type doped amorphous layers.

19. The heterojunction solar cell of claim 18, wherein the first and second transparent conductive film layers are disposed on the light receiving surface and comprise a first TCO film attached to the surface of the n-type doped amorphous layer and a second TCO film attached to the surface of the first TCO film, and the mass fraction of doped oxide in the first TCO film is greater than the mass fraction of doped oxide in the second TCO film.

20. The heterojunction solar cell of claim 19, wherein the mass fraction of doped oxide in the first TCO film is 5% to 20% and the mass fraction of doped oxide in the second TCO film is 0.5% to 5%.

21. The heterojunction solar cell of claim 19, wherein the first and second transparent conductive film layers on the light receiving surface further comprise a third TCO film attached to the surface of the second TCO film, wherein the mass fraction of doped oxide in the third TCO film is greater than the mass fraction of doped oxide in the second TCO film.

22. The heterojunction solar cell of claim 18, wherein the first transparent conductive film layer and the second transparent conductive film layer are located on the backlight surface and comprise a fourth TCO film attached to the surface of the p-type doped amorphous layer and a fifth TCO film attached to the surface of the fourth TCO film, and the mass fraction of doped oxide in the fourth TCO film is smaller than the mass fraction of doped oxide in the fifth TCO film.

23. The heterojunction solar cell of claim 1, 2, 3 or 8, wherein the thickness of the first and second transparent conductive film layers on the light receiving surface is less than or equal to the thickness of the first and second transparent conductive film layers on the backlight surface.

24. The heterojunction solar cell of claim 1, 2, 3 or 8, wherein one of the first and second transparent conductive film layers extends out of the side to cover the doped lateral side portion.

25. A method for fabricating a heterojunction solar cell according to any one of claims 1 to 24, comprising:

26. The method of claim 25, wherein the difference between the dimension of the first, second, third and fourth grooves and the corresponding dimension of the single-crystal silicon substrate is in the range of 2-4 mm.