TOPCon solar cell and grid line structure thereof

Abstract

The utility model relates to a TOPCon solar cell and a grid line structure thereof, the grid line structure is located on the front side and the back side of the TOPCon solar cell and comprises a main grid and a plurality of fine grids, the main grid is located on the surface of the TPPCon solar cell, the fine grids are arranged in the TPPCon solar cell, and the tops of the fine grids are in contact with the main grid. According to the utility model, the thin grids are hidden in the cell, so that the contact area between the thin grids and PN junctions can be increased, the surface reflectivity can be reduced, and the photoelectric conversion efficiency of the cell can be improved on the basis of not changing the number of grid lines.

Description

Technical Field

[0001] The utility model relates to the technical field of solar cells, in particular to a TOPCon solar cell and a grid line structure thereof. Background Art

[0002] Tunnel oxide passivated contact (TOPCon) solar cell is a new type of passivated contact solar cell first proposed by the Fraunhofer Institute for Solar Energy Research in Germany at the 28th European PVSEC Photovoltaic Conference in 2013. The cell first prepares a 1-2nm tunnel oxide layer on the back of the cell, and then deposits a layer of doped polysilicon. The two together form a passivated contact structure, providing good interface passivation for the back of the silicon wafer.

[0003] The existing TOPCon battery front and back grid lines are mainly composed of thin grids that occupy a large area of ​​the battery surface. The grid lines have a strong reflective effect on light. A large number of grid lines will affect the absorption of light, while a small number will affect the collection of carriers.

[0004] Therefore, the present invention designs a novel high-efficiency battery structure, which can hide the fine grids of the TOPCon battery structure while keeping the number of fine grids on the front and back sides unchanged, which obviously has practical significance. Utility Model Content

[0005] The utility model aims to provide a TOPCon solar cell and a grid line structure thereof.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a grid line structure of a TOPCon solar cell, located on the front and back sides of the TOPCon solar cell, including a main grid and a plurality of fine grids, wherein the main grid is located on the surface of the TPPCon solar cell, and the fine grid is arranged inside the TPPCon solar cell, and the top of the fine grid is in contact with the main grid.

[0007] Preferably, a silicon nitride layer A is provided on the top of the fine grid to hide the fine grid inside the TPPCon solar cell.

[0008] Preferably, the silicon nitride layer A is a six-layer film structure, including silicon nitride a, silicon nitride b, silicon nitride c, silicon oxynitride a, silicon oxynitride b and silicon dioxide.

[0009] Preferably, the thickness of silicon nitride a is 8±3nm; the thickness of silicon nitride b is 14±4nm; the thickness of silicon nitride c is 20±4nm; the thickness of silicon oxynitride a is 12±4nm; the thickness of silicon oxynitride b is 10±3nm; and the thickness of silicon dioxide is 6±2nm.

[0010] Preferably, the main grid is laid flat on the surface of the TPPCon solar cell, and the fine grid is perpendicular to the main grid.

[0011] In the above, the printing area of ​​the main grid occupies 10-80% of the area of ​​the surface of the TPPCon solar cell on which it is located; at the convergence of the fine grid and the main grid, the top of the fine grid contacts the main grid.

[0012] In the above, the main grid is sintered during printing to make the main grid contact with the top of the fine grid, ensuring that the carriers are gathered at the main grid position.

[0013] The present application also claims protection for a TOPCon solar cell, comprising a silicon substrate, wherein the silicon substrate is provided with the grid line structure of the TOPCon solar cell as described above on both the front and back sides.

[0014] Preferably, the front side of the silicon substrate is provided with a PN junction, a velvet structure, an aluminum oxide layer and a front silicon nitride layer from the inside to the outside, and a plurality of fine gates and a main gate are also provided on the front side of the silicon substrate.

[0015] In the above, fine gate positions are reserved on the front and back sides of the silicon substrate by laser patterning, the depth of the grooves is 5±1μm, and the width is 10±5μm; fine gate laser transfer is used to inject fine gate slurry into the laser grooved area and sinter once to form a fine gate.

[0016] Preferably, the front silicon nitride layer includes silicon nitride layer B and silicon nitride layer A; the fine gate on the front side of the silicon substrate is located below the silicon nitride layer A, and the fine gate on the front side of the silicon substrate passes through the silicon nitride layer B, the aluminum oxide layer, and the velvet structure to contact the PN junction.

[0017] Preferably, the silicon nitride layer A is a positive film; the silicon nitride layer B is a back film; the silicon nitride layer B is a three-layer film structure, including silicon nitride d: 20±2nm; silicon nitride e: 20±2nm; silicon nitride f: 50±5nm.

[0018] Preferably, the back side of the silicon substrate is provided with a tunneling oxide layer, a poly layer, and a back side silicon nitride layer from the inside to the outside, and a plurality of fine gates and a main gate are also provided on the back side of the silicon substrate.

[0019] Preferably, the back silicon nitride layer includes a silicon nitride layer A and a silicon nitride layer C; the fine gate on the back of the silicon substrate is located above the silicon nitride layer A, and the fine gate on the back of the silicon substrate passes through the silicon nitride layer C to contact the poly layer.

[0020] Preferably, the thickness of the silicon nitride layer C is 30 nm.

[0021] Due to the application of the above technical solution, the beneficial effects of the utility model are:

[0022] 1. The utility model can increase the contact area between the fine grid and the PN junction, reduce the surface reflectivity, and improve the photoelectric conversion efficiency of the battery without changing the number of grid lines by hiding the fine grid inside the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, some of the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is a schematic diagram of the overall structure of the TOPCon solar cell in the second embodiment of the present utility model.

[0025] Among them, 1. Silicon nitride layer A; 2. Silicon nitride layer B; 3. Aluminum oxide layer; 4. Velvet structure; 5. PN junction; 6. Silicon substrate; 7. Tunneling oxide layer; 8. Poly layer; 9. Silicon nitride layer C; 10. Front fine gate; 11. Back fine gate; 12. Front main gate. DETAILED DESCRIPTION

[0026] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] Embodiment 1

[0029] A grid line structure of a TOPCon solar cell is located on the front and back of the TOPCon solar cell, comprising a main grid and a plurality of fine grids, wherein the main grid is located on the surface of the TOPCon solar cell, the fine grid is arranged inside the TOPCon solar cell, and the top of the fine grid contacts the main grid.

[0030] Preferably, a silicon nitride layer A is provided on the top of the fine grid to hide the fine grid inside the TPPCon solar cell.

[0031] Preferably, the silicon nitride layer A is a six-layer film structure, including silicon nitride a, silicon nitride b, silicon nitride c, silicon oxynitride a, silicon oxynitride b and silicon dioxide.

[0032] Preferably, the thickness of silicon nitride a is 8±3nm; the thickness of silicon nitride b is 14±4nm; the thickness of silicon nitride c is 20±4nm; the thickness of silicon oxynitride a is 12±4nm; the thickness of silicon oxynitride b is 10±3nm; and the thickness of silicon dioxide is 6±2nm.

[0033] Preferably, the main grid is laid flat on the surface of the TPPCon solar cell, and the fine grid is perpendicular to the main grid.

[0034] In the above, the printing area of ​​the main grid occupies 10-80% of the area of ​​the surface of the TPPCon solar cell on which it is located; at the convergence of the fine grid and the main grid, the top of the fine grid contacts the main grid.

[0035] In the above, the main grid is sintered during printing to make the main grid contact with the top of the fine grid, ensuring that the carriers are gathered at the main grid position.

[0036] Embodiment 2

[0037] This embodiment is implemented on the basis of the above-mentioned embodiment 1, and the similarities with the above-mentioned embodiment 1 are not repeated here.

[0038] like Figure 1 As shown, this embodiment relates to a TOPCon solar cell, comprising a silicon substrate 6, wherein the silicon substrate is provided with the grid line structure of the TOPCon solar cell as described above on the front and back sides.

[0039] Preferably, the front side of the silicon substrate comprises a PN junction 5, a velvet structure 4, an aluminum oxide layer 3 and a front silicon nitride layer from inside to outside, and a plurality of front fine gates 10 and a front main gate 12 are arranged on the front side of the silicon substrate.

[0040] In the above, fine gate positions are reserved on the front and back sides of the silicon substrate by laser patterning, the depth of the grooves is 5±1μm, and the width is 10±5μm; fine gate laser transfer is used to inject fine gate slurry into the laser grooved area and sinter once to form a fine gate.

[0041] Preferably, the front silicon nitride layer includes a silicon nitride layer B2 and a silicon nitride layer A1; the front fine gate is located below the silicon nitride layer A, and the front fine gate passes through the silicon nitride layer B, the aluminum oxide layer, and the suede structure to contact the PN junction.

[0042] Preferably, the silicon nitride layer A is a positive film; the silicon nitride layer B is a back film; the silicon nitride layer B is a three-layer film structure, including silicon nitride d: 20±2nm; silicon nitride e: 20±2nm; silicon nitride f: 50±5nm.

[0043] Preferably, the back side of the silicon substrate is provided with a tunneling oxide layer 7, a poly layer 8, and a back side silicon nitride layer from the inside to the outside. The back side of the silicon substrate is also provided with a plurality of back side fine gates 11 and a back side main gate.

[0044] Preferably, the back silicon nitride layer includes a silicon nitride layer A1 and a silicon nitride layer C9; the back fine gate is located above the silicon nitride layer A, and the back fine gate passes through the silicon nitride layer C to contact the poly layer.

[0045] Preferably, the thickness of the silicon nitride layer C is 30 nm.

[0046] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A grid line structure of a TOPCon solar cell, characterized in that: Located on the front and back of the TOPCon solar cell, it includes a main grid and several fine grids. The main grid is located on the surface of the TPPCon solar cell, and the fine grid is arranged inside the TPPCon solar cell. The top of the fine grid is in contact with the main grid.

2. A grid line structure of a TOPCon solar cell according to claim 1, characterized in that: A silicon nitride layer A is provided on the top of the fine grid to hide the fine grid inside the TPPCon solar cell.

3. A grid line structure of a TOPCon solar cell according to claim 2, characterized in that: The silicon nitride layer A has a six-layer film structure, including silicon nitride a, silicon nitride b, silicon nitride c, silicon oxynitride a, silicon oxynitride b and silicon dioxide.

4. A grid line structure of a TOPCon solar cell according to claim 3, characterized in that: The thickness of the silicon nitride a is 8±3nm; the thickness of the silicon nitride b is 14±4nm; the thickness of the silicon nitride c is 20±4nm; the thickness of the silicon oxynitride a is 12±4nm; the thickness of the silicon oxynitride b is 10±3nm; and the thickness of the silicon dioxide is 6±2nm.

5. A grid line structure of a TOPCon solar cell according to claim 1, characterized in that: The main grid is laid flat on the surface of the TPPCon solar cell, and the fine grid is perpendicular to the main grid; at the convergence point of the fine grid and the main grid, the top of the fine grid contacts the main grid.

6. A TOPCon solar cell, characterized in that: It comprises a silicon substrate, wherein the front and back sides of the silicon substrate are provided with the grid line structure of the TOPCon solar cell according to any one of claims 1 to 5.

7. A TOPCon solar cell according to claim 6, characterized in that: The front side of the silicon substrate is provided with a PN junction, a velvet structure, an aluminum oxide layer and a front silicon nitride layer in order from the inside to the outside. The front side of the silicon substrate is also provided with a plurality of fine gates and a main gate.

8. A TOPCon solar cell as described in claim 7, wherein the front silicon nitride layer comprises a silicon nitride layer B and a silicon nitride layer A; the fine gate on the front side of the silicon substrate is located below the silicon nitride layer A, and the fine gate on the front side of the silicon substrate passes through the silicon nitride layer B, the aluminum oxide layer, and the suede structure to contact the PN junction.

9. A TOPCon solar cell according to claim 6, characterized in that: The back side of the silicon substrate is provided with a tunneling oxide layer, a poly layer, and a back side silicon nitride layer from the inside to the outside. The back side of the silicon substrate is also provided with a plurality of fine gates and a main gate.

10. A TOPCon solar cell according to claim 9, characterized in that: The back silicon nitride layer includes a silicon nitride layer A and a silicon nitride layer C; the fine gate on the back of the silicon substrate is located above the silicon nitride layer A, and the fine gate on the back of the silicon substrate passes through the silicon nitride layer C and contacts the poly layer.

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