A novel structure topcon cell and a preparation method thereof

Abstract

The application relates to the field of topcon cells, in particular to a novel structure topcon cell and a preparation method thereof, which comprises the following steps: (1) front texturing: performing texturing on the front surface of an n-type silicon substrate, and then performing boron diffusion to obtain an n-type silicon substrate containing a boron diffusion layer; (2) front passivation and anti-reflection: depositing a passivation layer on the front surface of the n-type silicon substrate containing the boron diffusion layer, and then depositing an anti-reflection layer on the passivation layer; (3) back through-passivation layer: depositing an ultrathin through-oxidation layer on the back surface of the n-type silicon substrate, then growing a polysilicon layer on the ultrathin through-oxidation layer, and performing phosphorus diffusion to form a phosphorus-doped polysilicon layer; and (4) printing electrodes. In the application, a plurality of groups of aluminum grid lines are used to replace a traditional full-aluminum back field on the back electrode, interval silver electrodes are adopted, and interconnection materials are used for connection, so that the prepared cell has little difference in performance from a traditional topcon cell, the consumption of aluminum and silver is reduced, and the production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of topcon battery technology, and specifically to a novel topcon battery structure. Background Technology

[0002] Fraunhofer ISE proposed a surface passivation method for n-type solar cells by using a stacked structure of a tunneling oxide layer and a doped amorphous silicon layer or a doped polycrystalline silicon layer to form a tunneling passivation contact structure on the back side. This structure creates band bending through the contact of two different semiconductors, preventing minority carriers from passing through, while majority carriers can tunnel through the ultrathin oxide layer and undergo short / multi-channel transport in the polycrystalline silicon layer for collection by the electrodes. In recent years, with the rapid development of n-Topcon solar cell technology, high efficiency and low cost have become unavoidable issues.

[0003] Currently, Topcon cells often employ multiple sets of silver grids for the back electrode, resulting in high silver paste consumption and cost. Furthermore, the arrangement of multiple silver grids makes it difficult to connect multiple cells in series. To address these issues, we propose a novel Topcon cell structure and its fabrication method. Summary of the Invention

[0004] (i) In view of the shortcomings of the prior art, the present invention provides a novel topcon battery structure that overcomes the shortcomings of the prior art, reduces the consumption of aluminum and silver, reduces production costs, and facilitates the stringing of battery cells.

[0005] (II) To achieve the above objectives, the present invention is implemented through the following technical solution: a novel topcon battery structure, comprising a silicon substrate, wherein the front side of the silicon substrate is provided with a boron diffusion layer, a passivation layer, an antireflection layer and a front electrode, and the back side of the silicon substrate is provided with an ultrathin tunnel oxide layer, a phosphorus-doped polycrystalline silicon layer and a back electrode.

[0006] This invention also provides a method for preparing a novel topcon battery structure, comprising the following steps:

[0007] (1) Front texturing: Texturing is performed on the front side of the n-type silicon substrate to form a pyramid structure, followed by boron diffusion to obtain an n-type silicon substrate with a boron diffusion layer;

[0008] (2) Front passivation and anti-reflection: A passivation layer is deposited on the front side of an n-type silicon substrate with a boron-containing diffusion layer by chemical vapor deposition, and then an anti-reflection layer is deposited on the passivation layer;

[0009] (3) Back tunnel passivation layer: An ultrathin tunnel oxide layer is deposited on the back of an n-type silicon substrate, and then a polycrystalline silicon layer is grown on the ultrathin tunnel oxide layer, and phosphorus diffusion is performed to form a phosphorus-doped polycrystalline silicon layer.

[0010] (4) Printed electrode: A front electrode is formed by printing Ag paste on the front side and a back electrode is set on the back side.

[0011] Preferably, in step (1), the boron doping concentration is 4E20cm⁻¹. -3 .

[0012] Preferably, in step (2), the passivation layer is an aluminum oxide layer with a thickness of 6 nm; the antireflection layer is a silicon nitride layer with a thickness of 85 nm.

[0013] Preferably, in step (3), the ultrathin tunnel oxide layer is an ultrathin silicon dioxide layer, and the thickness of the ultrathin tunnel oxide layer is 1.5 nm; the thickness of the polycrystalline silicon layer is 160 nm.

[0014] Preferably, in step (3), the phosphorus doping concentration is 5E20cm⁻¹. -3 .

[0015] Preferably, in step (4), the back electrode includes electrode 1, electrode 2, interconnect material 1 and interconnect material 2, electrode 1 and electrode 2 are connected, interconnect material 1 is connected to electrode 2, and interconnect material 1 and interconnect material 2 are connected.

[0016] Preferably, electrode 1 is an aluminum grid wire, electrode 2 is Ag paste, interconnect material 1 is Sn-B-Ag alloy, and interconnect material 2 is copper wire.

[0017] Preferably, each set of aluminum grid lines includes a main grid and three fine grids.

[0018] (III) This invention provides a novel topcon battery structure with the following advantages:

[0019] (1) The back electrode in this invention uses multiple sets of aluminum grid lines to replace the traditional all-aluminum back field and uses spaced silver electrodes, and then uses interconnect materials to connect them. The battery is almost the same as the traditional topcon battery in terms of performance, but the amount of aluminum used is reduced, the amount of silver consumed is also greatly reduced, and the production cost is reduced.

[0020] (1) The present invention uses interconnecting materials for connection, which eliminates the influence of the height difference between Al and Ag on the welding process, facilitates the string welding between battery cells, and improves the reliability of welding. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a traditional topcon battery structure.

[0022] Figure 2 This is a schematic diagram of the topcon battery structure of the present invention;

[0023] Figure 3This is a schematic diagram of the back electrode structure of the topcon battery of the present invention. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0025] Example 1

[0026] A novel topcon battery structure includes a silicon substrate. The front side of the silicon substrate has a boron diffusion layer, a passivation layer, an antireflection layer and a front electrode, and the back side of the silicon substrate has an ultrathin tunnel oxide layer, a phosphorus-doped polycrystalline silicon layer and a back electrode.

[0027] Example 2

[0028] A method for fabricating a novel topcon battery structure includes the following steps:

[0029] (1) Front-side texturing: A pyramid structure is formed on the front side of the n-type silicon substrate, followed by boron diffusion with a boron doping concentration of 4E20cm. -3 An n-type silicon substrate containing a boron diffusion layer was obtained.

[0030] (2) Front passivation antireflection: An aluminum oxide passivation layer with a thickness of 6 nm is deposited on the front side of an n-type silicon substrate containing a boron diffusion layer by vapor phase chemical deposition, and then an 85 nm thick silicon nitride antireflection layer is deposited on the passivation layer.

[0031] (3) Backside tunneling passivation layer: A 1.5 nm thick ultrathin silicon dioxide layer is deposited on the backside of an n-type silicon substrate. Then, a 160 nm thick polycrystalline silicon layer is grown on the ultrathin silicon dioxide layer, and phosphorus diffusion is performed to form a phosphorus-doped polycrystalline silicon layer. The phosphorus doping concentration is 5E20cm⁻¹. -3 .

[0032] (4) Printed electrode: A front electrode is formed by printing Ag paste on the front side and a back electrode is set on the back side.

[0033] The back electrode includes electrode 1, electrode 2, interconnect material 1 and interconnect material 2. Electrode 1 and electrode 2 are connected, interconnect material 1 is connected to electrode 2, and interconnect material 1 and interconnect material 2 are connected.

[0034] Electrode 1 is an aluminum grid line, electrode 2 is an Ag paste, interconnect material 1 is a Sn-B-Ag alloy, and interconnect material 2 is a copper wire.

[0035] Each group of aluminum grid lines includes a main grid and three fine grids. The main grid is 200 μm wide, and electrode 2 is 0.6 × 0.6 mm wide and 5 μm thick. Electrode 2 is located between two adjacent groups of aluminum grid lines.

[0036] Comparative Example 1

[0037] like Figure 1 As shown, it is basically the same as Example 2, except that the back electrode uses an all-aluminum back field with two sets of silver main grid lines.

[0038] Quality Inspection

[0039] Example 2 706.55 13.481 23.469 Comparative Example 1 707.92 13.466 23.854

[0040] The embodiments disclosed herein are preferred embodiments, but are not limited thereto. Those skilled in the art can readily grasp the spirit of the present invention based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. A novel topcon battery structure, characterized in that, The silicon substrate has a boron diffusion layer, a passivation layer, an anti-reflection layer and a front electrode on the front side, and an ultrathin tunnel oxide layer, a phosphorus-doped polycrystalline silicon layer and a back electrode on the back side. The back electrode includes electrode 1, electrode 2, interconnect material 1 and interconnect material 2. Electrode 1 and electrode 2 are connected, interconnect material 1 is connected to electrode 2, and interconnect material 1 and interconnect material 2 are connected. Among them, electrode 1 is an aluminum grid line, electrode 2 is Ag paste, interconnect material 1 is Sn-B-Ag alloy, and interconnect material 2 is copper wire. Each set of aluminum grid lines includes a main grid and three fine grids. The main grid has a width of 200 μm and a thickness of 5 μm.

2. The method for preparing a novel topcon battery as described in claim 1, characterized in that, Includes the following steps, (1) Front texturing: A pyramid structure is formed on the front side of the n-type silicon substrate, followed by boron diffusion to obtain an n-type silicon substrate with a boron diffusion layer; (2) Front passivation and anti-reflection: A passivation layer is deposited on the front side of an n-type silicon substrate with a boron-containing diffusion layer by chemical vapor deposition, and then an anti-reflection layer is deposited on the passivation layer; (3) Back tunnel passivation layer: An ultrathin tunnel oxide layer is deposited on the back of an n-type silicon substrate, and then a polycrystalline silicon layer is grown on the ultrathin tunnel oxide layer, and phosphorus diffusion is performed to form a phosphorus-doped polycrystalline silicon layer. (4) Printed electrode: A front electrode is formed by printing Ag paste on the front side and a back electrode is set on the back side.

3. The method for preparing a novel topcon battery as described in claim 2, characterized in that, In step (1), the boron doping concentration is 4E20cm. -3 .

4. The method for preparing a novel topcon battery structure as described in claim 2, characterized in that, In step (2), the passivation layer is an aluminum oxide layer with a thickness of 6 nm; the antireflection layer is a silicon nitride layer with a thickness of 85 nm.

5. The method for preparing a novel topcon battery as described in claim 2, characterized in that, In step (3), the ultrathin tunnel oxide layer is an ultrathin silicon dioxide layer, and the thickness of the ultrathin tunnel oxide layer is 1.5 nm; the thickness of the polycrystalline silicon layer is 160 nm.

6. The method for preparing a novel topcon battery structure as described in claim 2, characterized in that, In step (3), the phosphorus doping concentration is 5E20cm⁻¹. -3 .

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