CN218568850U - Back junction solar cell, photovoltaic module and power station - Google Patents

Abstract

The utility model discloses a back of body knot solar cell, photovoltaic module and power station. The back junction solar cell includes: a silicon substrate; the first tunneling oxide layer and the first passivation anti-reflection layer are alternately arranged on the front surface of the silicon substrate; a local first doped polysilicon layer laminated on the local first tunneling oxide layer to form a front surface field; a front electrode electrically connected to the front surface field; the local second tunneling oxide layer and the local second passivation antireflection layer are alternately arranged on the back surface of the silicon substrate; a local second doped polycrystalline silicon layer stacked on the second local tunneling oxide layer to form a back junction; and a back electrode electrically connected to the back junction. The back junction solar cell effectively improves the photoelectric conversion efficiency.

Description

Back junction solar cell, photovoltaic module and power station

Technical Field

The utility model relates to a back of body knot solar cell, photovoltaic module and power station.

Background

The back junction solar cell mainly refers to a cell with a surface field on the front surface and a PN junction structure on the back surface. At present, the front or back doped layer of the back junction solar cell generally covers the entire surface of the silicon substrate, and the design of covering the doped layer on the entire surface results in poor photoelectric conversion efficiency of the back junction solar cell.

SUMMERY OF THE UTILITY MODEL

In view of this, the utility model provides a back junction solar cell, photovoltaic module and power station, this back junction solar cell has reduced back junction solar cell's metal recombination owing to all set up the local tunneling oxide layer and the local polycrystalline silicon layer that dopes corresponding to the electrode on the front of silicon matrix and the back to can reduce the auger recombination of silicon matrix surface carrier, in addition, through the surperficial direct contact of passivation antireflection layer with the silicon matrix, can improve the light absorption of silicon matrix effectively, thereby improve back junction solar cell's photoelectric conversion efficiency effectively.

In order to solve the technical problem, the utility model provides a following technical scheme:

in a first aspect, the present invention provides a back junction solar cell, including:

a silicon substrate;

the first passivation antireflection layer comprises a plurality of first tunneling oxide layers and a plurality of first passivation antireflection layers, wherein the first tunneling oxide layers are arranged on the front surface of the silicon substrate at intervals and are in direct contact with the front surface;

a local first doped polycrystalline silicon layer stacked on each local first tunneling oxide layer to form a front surface field;

a front electrode electrically connected to the front surface field;

the first passivation antireflection layer and the second passivation antireflection layer are alternately arranged;

a local second doping polycrystalline silicon layer which is laminated on each local second tunneling oxide layer to form a back PN junction;

a back electrode electrically connected to the back junction.

In a second aspect, an embodiment of the present invention provides a photovoltaic module, including: the cell piece made of the back junction solar cell provided by the embodiment of the first aspect is provided.

In a third aspect, an embodiment of the present invention provides a power station, including: the embodiment of the second aspect provides a photovoltaic module.

Above-mentioned utility model's technical scheme of first aspect has following advantage or beneficial effect:

the utility model provides a back of body knot solar cell, because all set up local tunneling oxide layer and the local polycrystalline silicon layer that dopes corresponding to the electrode on the front and the back of silicon substrate, set up a plurality of local first tunneling oxide layers on the front of silicon substrate and range upon range of the local first polycrystalline silicon layer that dopes on each local first tunneling oxide layer promptly at the interval, form the front surface field, the front electrode is connected with the front surface field electricity, the interval sets up a plurality of local second tunneling oxide layers on the back of silicon substrate, the local second that cascades on each local second tunneling oxide layer dopes the polycrystalline silicon layer, form back PN junction; the back electrode is electrically connected with the PN junction, so that the metal recombination of the back-junction solar cell can be effectively reduced, and the Auger recombination of a silicon substrate surface carrier can be reduced. In addition, the passivated antireflection layer is in direct contact with the surface of the silicon substrate, namely a plurality of local first passivated antireflection layers are arranged on the front surface of the silicon substrate at intervals, namely the local first passivated antireflection layers and the local first tunneling oxide layers are alternately arranged, and a plurality of local second passivated antireflection layers are arranged on the back surface of the silicon substrate at intervals, namely the local second passivated antireflection layers and the local second tunneling oxide layers are alternately arranged, so that the light absorption of the silicon substrate can be effectively improved, and the photoelectric conversion efficiency of the back junction solar cell is effectively improved.

Drawings

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

fig. 2 is a schematic cross-sectional view of a second structure of a back junction solar cell according to an embodiment of the present invention;

fig. 3 is a schematic cross-sectional view of a third structure of a back junction solar cell according to an embodiment of the present invention;

fig. 4 is a schematic cross-sectional view of a fourth structure of a back junction solar cell provided in accordance with an embodiment of the present invention;

fig. 5 is a top view of a back junction solar cell provided in accordance with an embodiment of the present invention;

fig. 6 is a bottom view of a back junction solar cell provided in accordance with an embodiment of the present invention;

fig. 7 is a schematic cross-sectional view of a photovoltaic module according to an embodiment of the present invention.

The reference numbers are as follows:

1-a silicon substrate; 2-a local first tunnel oxide layer; 3-a local first passivation antireflective layer; 4-a local first doped silicon layer; 5-a front electrode; 51-front side fine grid; 52-front main grid; 6-local second tunneling oxide layer; 7-a local second passivation antireflective layer; 8-a local second doped polysilicon layer; 9-back electrode; 91-back side fine grid; 92-back side main gate; 101-a cover plate; 102-a back plate; 103-an encapsulation layer; 104-battery cell.

Detailed Description

The embodiment of the present invention relates to a structure stacked on another structure, which means that the structure is located directly above or below the another structure, and the structure is directly or indirectly contacted with the another structure to form a relatively fixed combination. For example, the local first doped polysilicon layer 4 shown in fig. 1 to 4 is stacked on the local first tunnel oxide layer 2, which means that the local first doped polysilicon layer 4 is located above the local first tunnel oxide layer 2, and one surface of the local first doped polysilicon layer 4 is in direct contact with one surface of the local first tunnel oxide layer 2, and forms a relatively fixed combination. The local second doped polysilicon layer 8 is stacked on each local second tunneling oxide layer 6, which means that the local second doped polysilicon layer 8 is located below the local second tunneling oxide layer 6, and one surface of the local second doped polysilicon layer 8 is in contact with one surface of the local second tunneling oxide layer 6, and forms a relatively fixed combination.

The front side generally refers to the side of the back junction solar cell that faces sunlight when in use. The back surface generally refers to the surface of the back junction solar cell that faces away from the sun when in use. Accordingly, the front electrode refers to an electrode located on the front side of the back junction solar cell, and the back electrode refers to an electrode located on the back side of the back junction solar cell.

The front and back surfaces of the silicon substrate are opposite surfaces of the silicon substrate having a relatively large area and serving as a light-receiving surface (a surface facing sunlight) or a backlight surface (a surface facing away from sunlight) of the solar cell. The terms "first" and "second" are used for distinguishing purposes only, and are not intended to limit the number or order of the components.

The connection or electrical connection of one structure to another structure according to embodiments of the present invention may mean that the one structure is in direct or indirect contact with another structure.

Research shows that the tunneling oxide layer and the doped polycrystalline silicon layer of the conventional back-junction solar cell are laminated and paved on the whole main surface of a silicon substrate, so that a current carrier is transited from a high level to a low level, energy is transferred to another electron through collision when the electron is compounded with a hole or the other hole can cause Auger recombination of the current carrier on the surface of the silicon substrate, a larger reverse saturation current is formed, and the antireflection effect of the antireflection layer is poor.

The problems that reverse saturation current formed by Auger recombination of an existing back junction solar cell and an antireflection effect of an antireflection layer are poor are solved. An embodiment of the utility model provides a back junction solar cell. Fig. 1 to 4 respectively show schematic cross-sectional views of back junction solar cells with different structures. As shown in fig. 1 to 4, the back junction solar cell may include:

a silicon substrate 1;

the first passivation anti-reflection layer comprises a plurality of local first tunneling oxide layers 2 and a plurality of local first passivation anti-reflection layers 3, wherein the local first tunneling oxide layers 2 are arranged on the front surface of a silicon substrate 1 at intervals and are in direct contact with the front surface, and the local first passivation anti-reflection layers 3 and the local first tunneling oxide layers 2 are alternately arranged;

a local first doped polysilicon layer 4 laminated on each local first tunneling oxide layer 2 to form a front surface field;

a front surface electrode 5 electrically connected to the front surface field;

the plurality of local second tunneling oxide layers 6 and the plurality of local second passivation anti-reflection layers 7 are arranged on the back surface of the silicon substrate 1 at intervals, wherein the local second passivation anti-reflection layers 7 and the local second tunneling oxide layers 6 are alternately arranged;

a local second doped polysilicon layer 8 stacked on each local second tunneling oxide layer 6 to form a back surface PN junction;

and a back electrode 9 electrically connected to the back PN junction.

It should be noted that, no diffusion layer is disposed on the front surface of the silicon substrate 1, and the local first tunneling oxide layer 2 and the local first passivation anti-reflection layer 3 are directly formed on the front surface of the silicon substrate 1 and directly contact with the front surface of the silicon substrate 1.

The thickness of the local first tunneling oxide layer 2 may be any value from 0.5nm to 3nm; for example, the thickness of the local first tunneling oxide layer 2 may be 0.5nm, 0.8nm, 1nm, 1.2nm, 1.5nm, 1.8nm, 2nm, 2.4nm, 2.7nm, 3nm, or the like.

In addition, the thickness of the local second tunneling oxide layer 6 may be any one value between 0.5nm and 3nm, for example, the thickness of the local second tunneling oxide layer 6 may be 0.5nm, 0.9nm, 1nm, 1.1nm, 1.4nm, 1.6nm, 2nm, 2.2nm, 2.5nm, 2.8nm, 3nm, or the like.

By controlling the thicknesses of the local first tunneling oxide layer 2 and the local second tunneling oxide layer 6, most of carriers can be tunneled, and meanwhile, the tunneling path of the carriers is reduced, so that the tunneling amount of the carriers is effectively increased, and the photoelectric conversion efficiency is realized.

The front electrode 5 is typically made of metal silver paste, so that current can be easily led out from the first doped silicon layer 4.

The back electrode 9 is typically made of metal silver paste or metal silver aluminum paste, so that current can be easily led out from the second doped polysilicon layer 8.

It can be understood that the front surface field formed by the local first tunnel oxide layer 2 and the local first doped polysilicon layer 4 is a local front surface field, and the position of the local front surface field corresponds to the position of the front electrode 5, and specifically, the projection of the position of the front electrode 5 on the front surface of the silicon substrate 1 falls on one local front surface field. I.e. the width of the local front surface field is typically larger than or equal to the width of the front electrode 5. In a preferred embodiment, the width of the local front surface field is greater than the width of the front electrode 5, which is beneficial to improve the photoelectric conversion efficiency of the back junction solar cell.

Wherein the width of the local front surface field is generally greater than or equal to the specific realization of the width of the front electrode 5: the width of the front electrode 5 is less than or equal to the width of the local first tunnel oxide layer 2 and the width of the local first doped polysilicon layer 4, and the width of the local first tunnel oxide layer 2 is greater than or equal to the width of the local first doped polysilicon layer 4. So as to satisfy the requirement that the width of the front electrode 5 is less than or equal to the width of the local front surface field, and to exert the function of the front electrode to the maximum extent.

In addition, the width of the back electrode 9 is less than or equal to the width of the local second tunnel oxide layer 6 and the width of the local second doped polysilicon layer 8, and the width of the local second tunnel oxide layer 6 is greater than or equal to the width of the local second doped polysilicon layer 8, so as to exert the function of the back electrode to the greatest extent.

The front surface electrode is electrically connected with the front surface field, the plurality of local second tunneling oxide layers are arranged on the back surface of the silicon substrate at intervals, and the local second doped polycrystalline silicon layer is laminated on each second local tunneling oxide layer to form a back surface PN junction; the back electrode is electrically connected with the PN junction, so that the metal recombination of the back-junction solar cell can be effectively reduced, and the Auger recombination of a silicon substrate surface carrier can be reduced. In addition, the passivated antireflection layer is in direct contact with the surface of the silicon substrate, namely the plurality of local first passivated antireflection layers are arranged on the front surface of the silicon substrate at intervals, the local first passivated antireflection layers and the local first tunneling oxide layers are alternately arranged, the plurality of local second passivated antireflection layers are arranged on the back surface of the silicon substrate at intervals, and the local second passivated antireflection layers and the local second tunneling oxide layers are alternately arranged, so that the light absorption of the silicon substrate can be effectively improved, and the photoelectric conversion efficiency of the back-junction solar cell is effectively improved.

Furthermore, because the passivation antireflection layer is formed in the area where the tunneling oxide layer and the doped polycrystalline silicon layer are not arranged on the front surface of the silicon substrate, the passivation antireflection layer is in direct contact with the surface of the silicon substrate, so that the antireflection effect and the passivation effect of the front surface of the solar cell are effectively improved, the short-circuit current of the solar cell can be increased by increasing the antireflection effect, the open-circuit voltage of the solar cell can be increased by increasing the passivation effect, and the photoelectric conversion efficiency of the solar cell can be improved to a certain extent.

In the embodiment of the present invention, as shown in fig. 2, the local first passivation anti-reflective layer 3 extends to the side of the local first tunneling oxide layer 2 and the side of the local first doped polysilicon layer 4 adjacent to the local first passivation anti-reflective layer to cover the side of the local first tunneling oxide layer 2 and the side of the local first doped polysilicon layer 4 adjacent to the local first passivation anti-reflective layer.

Further, as shown in fig. 2, the local second passivation anti-reflective layer 7 extends to the side of the local second tunnel oxide layer 6 and the side of the local second doped polysilicon layer 8 adjacent thereto, so as to cover the side of the local second tunnel oxide layer 6 and the side of the local second doped polysilicon layer 8 adjacent thereto. With the arrangement, after the local first tunneling oxide layer 2 and the first passivation anti-reflection layer 3 are formed on the front surface of the silicon substrate 1, and the local second tunneling oxide layer 6 and the second passivation anti-reflection layer 7 are formed on the back surface of the silicon substrate 1, the first passivation anti-reflection layer 3 can be conveniently and directly formed on the front surface of the silicon substrate 1, and the second passivation anti-reflection layer 7 can be conveniently formed on the back surface of the silicon substrate 1.

In addition, as shown in fig. 3 and fig. 4, in the case that the width of the front electrode 5 is smaller than the width of the local first doped polysilicon layer 4, the local first passivation anti-reflective layer 3 extends to the area on the local first doped polysilicon layer 4 not covered by the front electrode 5 through the side surface of the local first tunnel oxide layer 2 adjacent to the local first passivation anti-reflective layer;

further, as shown in fig. 3 and 4, in case the width of the back electrode 9 is smaller than the width of the local second doped polysilicon layer 8, the local second passivation anti-reflection layer 7 extends through the side of the local second tunnel oxide layer 6 adjacent to it to the area of the local second doped polysilicon layer 8 not covered by the back electrode 9.

That is, passivation antireflection layers are formed on the front and back surfaces of the silicon substrate 1 in addition to the front and back electrodes to prevent the passivation antireflection layers from shielding the front and back electrodes to prevent the electric conduction to the front and back electrodes, and at the same time, a passivation antireflection layer is formed by forming a passivation antireflection layer on a region other than the front and back electrodes, such as the side surface of the tunnel oxide layer, the region of the tunnel oxide layer not covered or shielded by the doped polysilicon layer, and the region of the doped polysilicon layer not covered or shielded by the electrode (the front or back electrode), to further improve the passivation antireflection effect.

In addition, for the front electrode 5 of the back junction solar cell provided by the embodiment of the present invention, fig. 5 shows a top view of the back junction solar cell. As shown in fig. 5, the front electrode 5 may include: a plurality of front fine grids 51 and a plurality of front main grids 52 crossed with the front fine grids 51, wherein each front fine grid 51 is electrically connected with the corresponding front surface field; each of the front surface main gates 52 is electrically connected to the plurality of front surface fine gates 51 to collect the current of the front surface fine gates 51. The front main grid is used as a bridge for collecting the current of the fine grid, and different numbers of the front fine grid and the back electrode are arranged on the premise that the numbers of the front main grid and the back electrode are consistent, so that the requirement of reducing the number of the front fine grid is better met, the effective area of the passivation anti-reflection layer on the front side of the silicon substrate is effectively increased, and the photoelectric conversion efficiency is improved.

Further, fig. 6 shows a bottom view of the back junction solar cell. As shown in fig. 6, the back electrode 9 includes: the semiconductor device comprises a plurality of back surface fine grids 91 and a plurality of back surface main grids 92 which are crossed with the back surface fine grids 91, wherein each back surface fine grid 91 is electrically connected with a back surface PN junction corresponding to the back surface fine grid 91; each of the back surface main gates 92 is electrically connected to the plurality of back surface fine gates 91 to collect the current of the back surface fine gates 91.

In the embodiment of the present invention, the number of the back fine grids 91 shown in fig. 6 is greater than that of the front fine grids 51, and the number of the back main grids 92 is equal to that of the front main grids 52. So as to meet the requirement of the subsequent battery serial connection. Therefore, the shielding of the front main grid 52 to the light on the front surface of the back junction solar cell can be reduced, and the photoelectric conversion efficiency can be improved.

The silicon substrate 1 of each of the above embodiments may be an N-type silicon substrate, and accordingly, the doping type of the local first doped polysilicon layer is an N-type, and the doping type of the local second doped polysilicon layer is a P-type. Thus, the front side of the back junction solar cell forms a front surface field and the back side forms a PN junction.

The silicon substrate 1 of each of the above embodiments may also be a P-type silicon substrate, and accordingly, the doping type of the first doped polysilicon layer is P-type, and the doping type of the second doped polysilicon layer is N-type. Similarly, the front surface of the back junction solar cell forms a front surface field, and the back surface forms a PN junction.

The back junction solar cell obtained based on the N-type or P-type silicon substrate can meet the requirements of different users.

The embodiment of the utility model provides a still provide a photovoltaic module, this photovoltaic module can include: a cell sheet made from the back junction solar cell of the above embodiment. Specifically, as shown in fig. 7, the photovoltaic module 100 may include: a cover plate 101, a back plate 102, an encapsulation layer 103, and battery cells 104 arranged in a matrix, wherein the battery cells 104 include a battery piece made of the back junction solar cell of the above embodiment. For example, the battery unit 104 may be a battery string formed by a plurality of battery pieces cut from the back junction solar battery of the above embodiment, or may be the back junction solar battery of the above embodiment directly.

The embodiment of the utility model provides a still provide a power station, this power station can include: the photovoltaic module that the above-mentioned embodiment provided.

The above description is only provided to help understand the structure and core idea of the present invention. For those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (10)

1. A back junction solar cell, comprising:

a silicon substrate (1);

the passivation structure comprises a plurality of local first tunneling oxide layers (2) and a plurality of local first passivation anti-reflection layers (3), wherein the local first tunneling oxide layers (2) are arranged on the front surface of the silicon substrate (1) at intervals and are in direct contact with the front surface, and the local first passivation anti-reflection layers (3) and the local first tunneling oxide layers (2) are alternately arranged;

a local first doped polysilicon layer (4) laminated on each local first tunneling oxide layer (2) to form a front surface field;

a front electrode (5) electrically connected to the front surface field;

a plurality of local second tunneling oxide layers (6) and a plurality of local second passivation anti-reflection layers (7) which are arranged on the back surface of the silicon substrate (1) at intervals, wherein the local second passivation anti-reflection layers (7) and the local second tunneling oxide layers (6) are alternately arranged;

a local second doped polysilicon layer (8) laminated on each local second tunneling oxide layer (6) to form a back PN junction;

and a back electrode (9) electrically connected to the back PN junction.

2. The back junction solar cell of claim 1,

the local first passivation anti-reflection layer (3) extends to the side surface of the local first tunneling oxide layer (2) adjacent to the local first passivation anti-reflection layer and the side surface of the local first doped polycrystalline silicon layer (4) to cover the side surface of the local first tunneling oxide layer (2) adjacent to the local first passivation anti-reflection layer and the side surface of the local first doped polycrystalline silicon layer (4);

and/or the presence of a gas in the gas,

the local second passivation antireflection layer (7) extends to the side surface of the local second tunneling oxide layer (6) adjacent to the local second passivation antireflection layer and the side surface of the local second doped polycrystalline silicon layer (8) to cover the side surface of the local second tunneling oxide layer (6) adjacent to the local second passivation antireflection layer and the side surface of the local second doped polycrystalline silicon layer (8).

3. The back junction solar cell of claim 1,

the front electrode (5) comprises: a plurality of front fine grids (51) and a plurality of front main grids (52) arranged to cross the front fine grids (51),

each front surface fine grid (51) is electrically connected with the corresponding front surface field;

each front main grid (52) is electrically connected with a plurality of front fine grids (51) so as to collect the current of the front fine grids (51);

the back electrode (9) comprises: a plurality of back surface fine grids (91) and a plurality of back surface main grids (92) which are crossed with the back surface fine grids (91),

each back surface fine gate (91) is electrically connected with the corresponding back surface PN junction;

each back surface main grid (92) is electrically connected with a plurality of back surface fine grids (91) so as to collect the current of the back surface fine grids (91);

the number of the back fine grids (91) is larger than that of the front fine grids (51), and the number of the back main grids (92) is equal to that of the front main grids (52).

4. The back junction solar cell of claim 1,

the width of the front electrode (5) is less than or equal to the width of the local first tunneling oxide layer (2) and the width of the local first doped polycrystalline silicon layer (4), and the width of the local first tunneling oxide layer (2) is greater than or equal to the width of the local first doped polycrystalline silicon layer (4);

and/or the presence of a gas in the atmosphere,

the width of the back electrode (9) is smaller than or equal to the width of the local second tunneling oxide layer (6) and the width of the local second doped polycrystalline silicon layer (8), and the width of the local second tunneling oxide layer (6) is larger than or equal to the width of the local second doped polycrystalline silicon layer (8).

5. The back junction solar cell of claim 4,

under the condition that the width of the front electrode (5) is smaller than that of the local first doped polycrystalline silicon layer (4), the local first passivation anti-reflection layer (3) extends to a region which is not covered by the front electrode (5) on the local first doped polycrystalline silicon layer (4) through the side surface of the adjacent local first tunneling oxide layer (2);

and/or the presence of a gas in the atmosphere,

in case the width of the back electrode (9) is smaller than the width of the local second doped polysilicon layer (8), the local second passivation anti-reflection layer (7) extends through the side of the local second tunnel oxide layer (6) adjacent to it to the area on the local second doped polysilicon layer (8) not covered by the back electrode (9).

6. The back junction solar cell of claim 1,

the front electrode (5) is made of metal silver paste;

and/or the presence of a gas in the atmosphere,

the back electrode (9) is made of metal silver paste or metal silver aluminum paste.

7. The back junction solar cell of claim 1,

the thickness of the local first tunneling oxide layer (2) is 0.5-3 nm;

and/or the presence of a gas in the gas,

the thickness of the local second tunneling oxide layer (6) is 0.5 nm-3 nm.

8. The back junction solar cell of claim 1,

the silicon substrate (1) is an N-type silicon substrate, the doping type of the local first doped polycrystalline silicon layer (4) is N-type, and the doping type of the local second doped polycrystalline silicon layer (8) is P-type; or,

the silicon substrate (1) is a P-type silicon substrate, the doping type of the local first doping polycrystalline silicon layer (4) is P-type, and the doping type of the local second doping polycrystalline silicon layer (8) is N-type.

9. A photovoltaic module, comprising: a cell sheet made from the back junction solar cell of any of claims 1 to 8.

10. A power plant, characterized in that it comprises: the photovoltaic module of claim 9.

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