Patent ID: 12230723

In the drawings:1, Substrate;11-1, P+layer;11-2, AlOx film layer;11-3, Front-side SiNxHy film layer;11-4, H-type metal grid line electrode,12-1, SiOx film layer;12-2, Poly-Si film layer;12-3, Back-side SiNxHy film layer;12-4, First silver fine grid;12-5, First silver main grid;12-6, Second aluminum fine grid;12-7, Second aluminum main grid.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Specific implementations of the present disclosure are further described below.

Unless otherwise specified, raw materials used in the present disclosure are commercially available or commonly used in the art; and unless otherwise specified, methods in the following embodiments are conventional in the art.

Embodiment 1

A back-side metal electrode of an N-type TOPCon solar cell includes a substrate1; a back side of the substrate is provided with an N+ layer by means of P diffusion; a back-side passivation film is provided on the N+ layer, and consists of an SiOx film layer12-1, a Poly-Si film layer12-2and a back-side SiNxHy film layer12-3; and the back-side passivation film is provided with a first silver fine grid12-4, a second aluminum fine grid12-6, a second aluminum main grid12-7and a first silver main grid12-5. The second aluminum fine grid is prepared by overprinting aluminum paste on the first silver fine grid; the first silver fine grid is arranged perpendicular to the first silver fine grid, and include a plurality of grid segments which are disposed interval; and the second aluminum main grid is filled and printed between any two adjacent grid segments of the plurality of grid segments and around each of the plurality of grid segments, so as to make the first silver main grids form a partial contact with the second aluminum main grids.

The method for preparing the above back-side metal electrode of an N-type TOPCon solar cell includes the following steps:

(1) An SiOx film layer and a Poly-Si film layer are deposited on the back side of the substrate by means of LPCVD, and an N+-doped Poly-Si film layer is formed by means of P diffusion; then the back-side SiNxHy film layer is deposited by means of LPCVD, so as to form a back-side passivation film; and a thickness of the SiOx film layer is 1 nm, a thickness of the Poly-Si film layer is 100 nm, and a thickness of the back-side SiNxHy film layer is 50 nm.

(2) As shown inFIG.1(a), the plurality of first silver fine grids12-4and the plurality of first silver main grids12-5, which are perpendicular to each other, are formed by synchronously printing the silver paste on the back-side SiNxHy passivation film. A number of the plurality of first silver fine grids is 106, and a width of each of the plurality of first silver fine grids is 40 μm, and a height of each of the plurality of first silver fine grids is 10 μm; and a number of the plurality of first silver main grids is 5, the plurality of grid segments in each of the first silver main grids is 4, and each of the plurality of grid segments has a length of 4 mm, a width of 0.1 mm and a height of 4 μm.

(3) As shown inFIG.1(b), the plurality of second aluminum fine grids12-6are formed by overprinting the aluminum paste on the plurality of first silver fine grids; and the plurality of second aluminum main grids12-7are formed, in a printing manner, between any two adjacent grid segments of the plurality of grid segments and around each of the plurality of grid segments. A number of the plurality of second aluminum fine grids is 106, with the width being 45 μm and the height being 20 μm; and a number of the plurality of second aluminum main grids is 5, with the width being 0.3 μm and the height being 10 μm. In this way, the back-side metal electrode1(c) in which the plurality of first silver main grids are in partial contact with the plurality of second aluminum main grids is obtained by means of metal screen printing.

In the N-type TOPCon solar cell including the back-side metal electrode, as shown inFIG.2, a front side of the substrate of the cell is formed with a P+layer11-1by means of B diffusion, is provided with a front-side anti-reflection coating, which including an AlOx film layer11-2deposited by means of ALD and a front-side SiNxHy film layer11-3deposited by means of PECVD. A thickness of the AlOx film layer is 6 nm, and a thickness of the front-side SiNxHy film layer is 70 nm. Then, an H-type metal grid line electrode11-4is prepared by printing and sintering silver and aluminum paste on the front-side anti-reflection coating; the main grid is 9BB; and the number of fine grid is 106, with the width being 35 μm and the height being 15 μm.

Embodiment 2

A back-side metal electrode of an N-type TOPCon solar cell. The difference between these embodiments and the above embodiments lies in that, the number of the plurality of first silver fine grids is 122, with the width being 30 μm and the height being 10 μm; the number of the plurality of first silver main grids is 8, the number of the plurality of grid segments in each first silver main grid is 8, and each grid segment has a length of 8 mm, a width of 1 mm and a height of 6 μm; the number of the plurality of second aluminum fine grids is 122, with the width being 35 μm and the height being 15 μm; and the number of the plurality of second aluminum main grids is 8, with the width being 2.0 μm and the height being 15 μm.

Embodiment 3

A back-side metal electrode of an N-type TOPCon solar cell. The difference between these embodiment and the above embodiments lies in that, the number of the plurality of first silver fine grids is 110, with the width being 25 μm and the height being 5 μm; the number of the plurality of first silver main grids is 12, the number of the plurality of grid segments in each first silver main grid is 12, and each grid segment has a length of 2 mm, a width of 2 mm and a height of 8 μm; the number of the plurality of second aluminum fine grids is 110, with the width being 40 μm and the height being 10 μm; and the number of the plurality of second aluminum main grids is 12, with the width being 3.0 μm and the height being 30 μm.

Comparative Example 1

A back-side metal electrode of an N-type TOPCon solar cell is prepared by completely printing silver paste; and specific structure parameters are as follows: the number of silver grids is 116, with the width being 40 μm and the height being 13 μm; and the rest is the same as that in Embodiment 1.

Then an N-type TOPCon solar cell is prepared by using the back-side metal electrode in Comparative example 1; and the remaining structures and parameters are the same as that of the N-type TOPCon solar cell in Embodiment 1.

Performance Test

The performance processes of the N-type TOPCon solar cell obtained in Embodiments 1-3 and Comparative example 1 are tested, and results are shown in the figures below.

Short-Open-Seriescircuitcircuitresis-FillConversioncurrentvoltagetancefactorefficiencyItemIsc(mA/cm2)Uoc(V)Rs(mΩ)(FF %)(Ncell %)Embodiment 140.660.7061.782.2723.62Embodiment 240.660.7021.482.7223.61Embodiment 340.660.7001.283.0223.63Comparative40.660.7061.981.9723.54example 1

It can be seen, from the above table, that compared with complete silver paste, using the technical solution of the present application can improve the conversion efficiency and fill factor of the N-type TOPCon solar cell, significantly reduces the size of the series resistance, and is lower in cost compared to complete silver paste.