CN212848451U - Heterojunction solar cell - Google Patents

Heterojunction solar cell Download PDF

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CN212848451U
CN212848451U CN202021770990.4U CN202021770990U CN212848451U CN 212848451 U CN212848451 U CN 212848451U CN 202021770990 U CN202021770990 U CN 202021770990U CN 212848451 U CN212848451 U CN 212848451U
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intrinsic
amorphous layer
doped
film
layer
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张达奇
姚铮
吴华德
吴坚
蒋方丹
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Jiaxing Canadian Solar Technology Research Institute
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Jiaxing Atlas Photovoltaic Technology Co Ltd
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Abstract

The utility model provides a heterojunction solar cell and preparation method thereof, wherein have the amorphous layer on the monocrystalline silicon substrate side of heterojunction solar cell, based on the utility model provides a concrete structure of heterojunction solar cell can avoid forming direct contact between first transparent conductive film layer, the transparent conductive film layer of second and the monocrystalline silicon substrate and lead to the electric leakage, reduces the impaired risk in monocrystalline silicon substrate edge, and the side of monocrystalline silicon substrate can also effectively improve the passivation effect of monocrystalline silicon substrate side owing to covered by intrinsic structure membrane.

Description

Heterojunction solar cell
Technical Field
The utility model relates to a photovoltaic field of making especially relates to a heterojunction solar cell.
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.
SUMMERY OF THE UTILITY MODEL
The utility model discloses aim at solving one of the technical problem that prior art exists at least, for realizing the utility model purpose of the aforesaid, the utility model provides a heterojunction solar cell, its concrete design 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 an intrinsic structure film covering the monocrystalline silicon substrate, a doped structure film covering the intrinsic structure film, a first transparent conductive film layer covering the doped structure film and positioned on the first main surface side, a first collector electrode positioned on the first transparent conductive film layer, a second transparent conductive film layer covering the doped structure film and positioned on the second main surface side, and a second collector electrode positioned on the second transparent conductive film layer; the intrinsic structure film comprises a first intrinsic amorphous layer located on the first main surface and a second intrinsic amorphous layer located on the second main surface, the first intrinsic amorphous layer is provided with a first intrinsic side edge part extending towards the direction of the second intrinsic amorphous layer to cover the whole side surface and a first intrinsic back surface extension part covering the edge area of the second main surface, the second intrinsic amorphous layer is provided with a second intrinsic side edge part extending towards the direction of the first intrinsic amorphous layer to cover the first intrinsic side edge part; the doped structure film comprises a first doped amorphous layer located on the first main face side and a second doped amorphous layer located on the second main face side and having the doping type opposite to that of the first doped amorphous layer.
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.
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 first doped amorphous layer and the second doped amorphous layer have doped side portions extending out of the side surfaces, and the doped side portions of the first doped amorphous layer and the doped side portions of the second doped amorphous layer are stacked outside the second intrinsic side 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 intrinsic films stacked.
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 an intrinsic amorphous silicon oxide film.
Further, one of the first doped amorphous layer and the second doped amorphous layer, which is located on one side of the light receiving surface, is an n-type doped amorphous layer, and one of the first doped amorphous layer and the second doped amorphous layer, which is located on one side of the backlight surface, is a p-type doped amorphous layer.
Furthermore, 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 doped with an oxide with a mass ratio smaller than that of the doped oxide in the first TCO film.
Further, the first transparent conductive film layer and the second transparent conductive film layer which are positioned on the light receiving surface also comprise a third TCO film which is attached to the surface of the second TCO film and has a doped oxide mass ratio larger than that of the mixed oxide 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 doped with an oxide with a mass ratio larger than that of a doped oxide in the fourth 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 utility model has the advantages that: based on the heterojunction solar cell provided by the utility model, the direct contact between the first transparent conductive film layer, the second transparent conductive film layer and the monocrystalline silicon substrate can be avoided to cause electric leakage, and the risk of damage to the edge of the monocrystalline silicon substrate is reduced; and the side surface of the monocrystalline silicon substrate is covered by the intrinsic structure film, 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 required to be 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 the heterojunction solar cell of the present 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 diagram of a second embodiment of the heterojunction solar cell of the present invention;
fig. 9 is a schematic diagram of a third embodiment of the heterojunction solar cell of the present invention;
fig. 10 is a schematic diagram illustrating a fourth embodiment of the heterojunction solar cell of the present invention;
fig. 11 is a schematic diagram of a fifth embodiment of the heterojunction solar cell of the present invention;
fig. 12 is a schematic diagram illustrating a state of the first intrinsic amorphous layer in the heterojunction solar cell according to the present invention;
fig. 13 is a schematic diagram illustrating a state of the second intrinsic amorphous layer in the heterojunction solar cell of the present invention;
fig. 14 is a schematic diagram illustrating a state of a first doped amorphous layer in a heterojunction solar cell according to the present invention;
fig. 15 is a schematic diagram illustrating a state of a second doped amorphous layer in a heterojunction solar cell according to the present invention;
fig. 16 is a schematic diagram illustrating a state of the transparent conductive film layer in the heterojunction solar cell according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
Referring to fig. 2, 8, 9, 10 and 11, the heterojunction solar cell according to the present invention includes a single crystal silicon substrate 10. The single crystal silicon substrate 10 has a first main surface 101 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.
The utility model relates to a heterojunction solar cell still includes to cover the intrinsic structure membrane outside monocrystalline silicon substrate 10, covers the doping structure membrane outside the intrinsic structure membrane, covers the first transparent conductive film layer 41 that just is located first main face side outside the doping structure membrane, is located first collecting electrode 51 on the first transparent conductive film layer 41, covers the second transparent conductive film layer 42 that just is located second main face side outside the doping structure membrane and is located the second collecting electrode 52 on the second transparent conductive film layer 42.
More specifically, the intrinsic structure film in the present invention includes a first intrinsic amorphous layer 21 on a first main surface and a second intrinsic amorphous layer 22 on a second main surface. Referring to fig. 2, 8, 9, 10, and 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 extends circumferentially to cover the entire side of the single crystal silicon substrate 10, and the first intrinsic amorphous layer 21 further has a first intrinsic back surface extension 2100 covering the edge region of the second 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. It will be appreciated that in particular implementations, the first intrinsic side edge portion 210 is integrally formed with the first intrinsic backside extension 2100 and the portion of the second intrinsic amorphous layer 22 on the second major surface forms a cover for the first intrinsic backside extension 2100.
The doped structured film of the present invention includes a first doped amorphous layer 31 on the first principal surface 101 side and a second doped amorphous layer 32 on the second principal surface 102 side.
Based on the utility model provides a heterojunction solar cell can avoid forming direct contact between first transparent conductive film layer 41, the transparent conductive film layer 42 of second and the monocrystalline silicon substrate 10 and lead to the electric leakage, reduces the impaired risk in monocrystalline silicon substrate 10 edge. The utility model discloses the side of single crystal silicon substrate 10 is covered by intrinsic structure membrane, can effectively improve the passivation effect of single crystal silicon substrate 10 side for heterojunction solar cell has higher photoelectric conversion efficiency than the battery piece that the edge was not passivated among the prior art.
In some embodiments of the present invention, no connection may be formed between the first doped amorphous layer 31 and the second doped amorphous layer 32; however, as a preferred embodiment of the present invention, the first doped amorphous layer 31 and the second doped amorphous layer 32 both have doped side portions extending to the outside of the side surface 103 and forming a connection with each other, so as to form a better protection for the side surface 103 of the single crystal silicon substrate 10.
In the specific implementation process of the present invention, the doped side edge portions of the first doped amorphous layer 31 and the second doped amorphous layer 32 can be directly formed by attaching to the side surface; it is preferable that 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 outside the second intrinsic side edge portion 220.
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 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 of the present invention is located on a side surface of the first doped amorphous layer 31 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 shown in fig. 2 and 8 of the present invention, 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 of the 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 backlight 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 utility model, in order to ensure that monocrystalline silicon substrate 10 side has better passivation effect, in the concrete implementation process, the sum of the partial thickness that first intrinsic side portion 21 and second intrinsic side portion 22 covered first intrinsic side portion 21 is not less than 1nm, and the thickness that second intrinsic side portion 22 covered the regional part of side and the continuous one side of second principal face is not less than 1nm either.
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 an intrinsic amorphous silicon film, an intrinsic amorphous silicon oxide film, and an intrinsic amorphous silicon carbide film.
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.
The utility model discloses in, because first intrinsic amorphous layer 21 and second intrinsic amorphous layer 22 all include the intrinsic membrane of at least two-layer range upon range of setting, in the concrete implementation in-process, can be convenient for through the characteristic of controlling each rete, and then form the better first intrinsic amorphous layer 21 of comprehensive properties and second intrinsic amorphous layer 22.
As a preferred embodiment of the present invention, in the specific implementation process, the layer of the intrinsic film of the first intrinsic amorphous layer 21 farthest from the single crystal silicon substrate 10 is set as an intrinsic amorphous silicon oxide film. 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 can also be set as intrinsic amorphous silicon oxide, i.e. the sixth intrinsic film 206 farthest from the single crystal silicon substrate 10 in this embodiment can be set as intrinsic amorphous silicon oxide film.
The intrinsic amorphous silicon oxide film has a lower passivation effect than the intrinsic amorphous silicon film and the intrinsic amorphous silicon carbide film, but has a better light transmittance than the intrinsic amorphous silicon film and the intrinsic amorphous silicon carbide film, and in the heterojunction solar cell, the 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 film with the optimal light transmittance can optimize the photoelectric conversion efficiency of the heterojunction solar cell to a certain extent.
As a further preferred feature of the present invention, in the present invention, the intrinsic film hydrogen content near the single crystal silicon substrate 10 in the first intrinsic amorphous layer 21 is higher than the intrinsic film hydrogen content far from the single crystal silicon substrate, and the intrinsic film hydrogen content near the single crystal silicon substrate 10 in the second intrinsic amorphous layer 22 is higher than the intrinsic film hydrogen content 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 preferred aspect of the present invention, when the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 respectively include three intrinsic films stacked on each other, the hydrogen content of the three intrinsic films of the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 respectively ranges from 20% to 40%, from 10% to 25% and from 8% to 20% in the 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 preferred 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 thickness ranges 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 1 to 3nm, 2 to 4nm and 1 to 3nm in this order, and the thickness ranges 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 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.
As a further preferred aspect, the ratio of bonded hydrogen atoms in the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 is 15% to 25% of the total hydrogen atoms. When specific passivation is used, bonding hydrogen atom plays decisive role, and bonding hydrogen atom accounts for about 10% usually in the intrinsic layer amorphous layer among the prior art to total hydrogen atom ratio, the utility model discloses in through improving bonding hydrogen atom accounts for total hydrogen atom's ratio in first intrinsic amorphous layer 21 and the intrinsic amorphous layer 22 of second, also can improve the passivation effect of first intrinsic amorphous layer 21 and the intrinsic amorphous layer 22 of second to monocrystalline silicon substrate 10 surface, and then further improve the open circuit voltage of corresponding heterojunction solar wafer.
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. The utility model discloses in through the hydrogen atom concentration that improves in first intrinsic amorphous layer 21 and the intrinsic amorphous layer 22 of second, can effectively improve the passivation effect of first intrinsic amorphous layer 21 and the intrinsic amorphous layer 22 of second to monocrystalline silicon substrate 10 surface, and then improve the open circuit voltage of corresponding heterojunction solar wafer.
In the present invention, preferably, the first doped amorphous layer 31 and the second doped amorphous layer 32 are located on one side of the light receiving surface and are n-type doped amorphous layers, and the first doped amorphous layer 31 and the second doped amorphous layer 32 are located on one side of the backlight surface and are p-type doped amorphous layers. 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.
When the first doped amorphous layer 31 and the second doped amorphous layer 32 are located on the light receiving surface side and are n-type doped amorphous layers, and the first doped amorphous layer 31 and the second doped amorphous layer 32 are located on the backlight surface side and are p-type doped amorphous layers, the present invention relates to a first transparent conductive film 41 and a second transparent conductive film 42 further having 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 a specific implementation process, the carrier concentration in the first TCO film 401 and the second TCO film 402 is in a positive correlation with the mass ratio of the doped oxide in the corresponding film layers, but in a specific manufacturing process, the carrier concentration can be further adjusted to some extent by controlling the film forming 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.
As further shown in fig. 6, in other embodiments of the present 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, and the mass ratio of the doped oxide in the third TCO film 403 is greater than the mass ratio 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 embodiment structures shown in fig. 9 and 10 of the present invention, the second transparent conductive film layer 42 is located on the light receiving surface and the first transparent conductive film layer 41 is located on the backlight surface of the first transparent conductive film layer 41 and the second transparent conductive film layer 42. 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 to the outside 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.
For better understanding the utility model discloses, the utility model also provides a heterojunction solar cell's manufacturing method, this method is used for making as above heterojunction solar cell, and it includes:
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.
A first intrinsic amorphous layer manufacturing step, referring to fig. 12, a single crystal silicon substrate 10 is placed on a first carrier plate 61 with a first main surface facing upward, the first carrier plate 61 has a first groove 610 for placing the single crystal silicon substrate 10, a first intrinsic amorphous layer 21 is deposited on the first main surface side of the single crystal silicon substrate 10 from the upper side of the first carrier plate 61, the periphery of the first intrinsic amorphous layer 21 extends to cover the whole side surface and the edge area of the second main surface, in this embodiment, the periphery of the first intrinsic amorphous layer 21 extends to cover the whole side surface to form a first intrinsic side edge portion 210, and the portion of the first intrinsic amorphous layer 21 covering the edge area of the second main surface to form a first intrinsic back surface extension portion 2100.
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. It is understood that in the second intrinsic amorphous layer fabrication step, the portion of the second intrinsic side edge portion 220 located at the second main surface covers the first intrinsic backside extension 2100.
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 specific implementation process 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 plate 62 involved in the second intrinsic amorphous layer manufacturing step and the fourth carrier plate 64 involved in the second doped amorphous layer manufacturing step can be the same carrier plate, and in the two-step execution process, the monocrystalline silicon substrate 10 does not need to be moved.
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 and the second main surface facing upward may also be placed on a fifth carrier 70 (not shown), 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 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.
The utility model discloses in, in monocrystalline silicon substrate system fine hair step, utilize earlier to dilute the HF solution that the solubility is 5% and get rid of the surface oxide layer, recycle monocrystalline silicon's anisotropic corrosion characteristic, adopt KOH or NaOH or tetramethyl ammonium hydroxide (TMAH) to add the solution of mellow wine and carry out the system fine hair.
The four 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 involved in the utility model are all formed by adopting PECVD deposition process. The first transparent conductive film layer 41 and the second transparent conductive film layer 42 involved in the utility model are formed by PVD deposition, RPD deposition or magnetron sputtering deposition process. The first collector electrode 51 and the second collector electrode 52 according to the present invention are formed by a screen printing process.
For better understanding the utility model discloses, following still demonstrates a concrete mode of making of heterojunction solar wafer four-layer amorphous layer: 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 a first intrinsic amorphous layer 21 under the action of a radio frequency power supply of 13.56 MHz; 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 the first doping by using the same gasAn amorphous layer 31; 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.
The above shows only the preparation manner in which the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 are all made of intrinsic amorphous silicon, and it can be understood that in other embodiments of the present invention, the intrinsic films of the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 may also be intrinsic amorphous silicon oxide or intrinsic amorphous silicon carbide. 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 fabricating the first doped 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. The utility model discloses in, doping amorphous silicon oxide film, doping amorphous silicon carbide film or doping amorphous silicon carbide/doping amorphous silicon oxide complex film 302 can increase the optical band gap of heterojunction solar cell photic surface rete, increases the printing opacity, can promote the optical property of battery.
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 list of details is only for the practical implementation of the present invention, and they are not intended to limit the scope of the present invention, and all equivalent implementations or modifications that do not depart from the technical spirit of the present invention should be included in the scope of the present invention.

Claims (20)

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 an intrinsic structure film covering the monocrystalline silicon substrate, a doped structure film covering the intrinsic structure film, a first transparent conductive film layer covering the doped structure film and positioned on the first main surface side, a first collector electrode positioned on the first transparent conductive film layer, a second transparent conductive film layer covering the doped structure film and positioned on the second main surface side, and a second collector electrode positioned on the second transparent conductive film layer; the intrinsic structure film comprises a first intrinsic amorphous layer located on the first main surface and a second intrinsic amorphous layer located on the second main surface, the first intrinsic amorphous layer is provided with a first intrinsic side edge part extending towards the direction of the second intrinsic amorphous layer to cover the whole side surface and a first intrinsic back surface extension part covering the edge area of the second main surface, the second intrinsic amorphous layer is provided with a second intrinsic side edge part extending towards the direction of the first intrinsic amorphous layer to cover the first intrinsic side edge part; the doped structure film comprises a first doped amorphous layer located on the first main face side and a second doped amorphous layer located on the second main face side and having the doping type opposite to that of the first doped amorphous layer.
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, 2 or 3, 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.
9. The heterojunction solar cell of claim 8, 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.
10. The heterojunction solar cell of claim 1, 2 or 3, 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 with a doping concentration higher than that of the third doped amorphous silicon film, from the light receiving surface to the backlight surface.
11. The heterojunction solar cell of claim 1, 2 or 3, wherein the first and second doped amorphous layers each have a doped side portion extending out of the side, the doped side portion of the first doped amorphous layer and the doped side portion of the second doped amorphous layer being stacked outside the second intrinsic side portion.
12. The heterojunction solar cell of claim 1, 2 or 3, 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 region where the side surface is connected to the second main surface are not less than 1 nm.
13. The heterojunction solar cell of claim 1, 2 or 3, wherein the first and second intrinsic amorphous layers each comprise at least two intrinsic films disposed one on top of the other.
14. The heterojunction solar cell of claim 13, 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 an intrinsic amorphous silicon oxide film.
15. The heterojunction solar cell of claim 1, 2 or 3, wherein one of the first and second doped amorphous layers on the light receiving surface side is an n-type doped amorphous layer, and one of the first and second doped amorphous layers on the backlight surface side is a p-type doped amorphous layer.
16. The heterojunction solar cell of claim 15, 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 having a smaller mass fraction of doped oxide than the mass fraction of doped oxide in the first TCO film.
17. The heterojunction solar cell of claim 16, 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 and having a higher mass fraction of doped oxide than the second TCO film.
18. The heterojunction solar cell of claim 15, wherein the first transparent conductive film layer and the second transparent conductive film layer are on the back light side 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 having a mass fraction of doped oxide greater than a mass fraction of doped oxide in the fourth TCO film.
19. The heterojunction solar cell of claim 1, 2 or 3, wherein the thickness of the first transparent conductive film layer and the second transparent conductive film layer on the light receiving surface is less than or equal to the thickness of the first transparent conductive film layer and the second transparent conductive film layer on the backlight surface.
20. The heterojunction solar cell of claim 1, 2 or 3, wherein the first and second doped amorphous layers each have a doped lateral edge portion extending out of the lateral side and forming a connection with each other, one of the first and second transparent conductive film layers extending out of the lateral side to cover the doped lateral edge portion.
CN202021770990.4U 2020-08-21 2020-08-21 Heterojunction solar cell Active CN212848451U (en)

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