N-type TOPCon cell with double-sided aluminum paste electrodes, and preparation method for preparing N-type TOPCon cell with double-sided aluminum paste electrodes

Abstract

Some embodiments of the present disclosure provide an N-type TOPCon cell with double-sided aluminum paste electrodes, and a preparation method therefor. The front side of the cell is provided with a front-side silver main grid and a front-side aluminum fine grid, and the back side is provided with a back-side silver main grid and a back-side aluminum fine grid. The method for preparing the cell includes: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.P diffusion on the back side.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on the front side.fwdarw.deposition of a second preparatory layer SiN.sub.xH.sub.y on the back side.fwdarw.UV laser ablation on the front side of the substrate and the back side of the substrate.fwdarw.screen printing.

Claims

1. A preparation method for preparing an N-type TOPCon cell with double-sided aluminum paste electrodes, wherein an N-type TOPCon cell comprises an N-type substrate; a P-type doped region layer, an AlO.sub.x layer and a first SiN.sub.xH.sub.y layer are successively provided, from inside to outside, on a front side of the N-type substrate; a tunnel oxide layer, an N-type doped polysilicon layer and a second SiN.sub.xH.sub.y layer are successively provided, from inside to outside, on a back side of the N-type substrate; front-side silver main grids and front-side aluminum fine grids are provided on the first SiN.sub.xH.sub.y layer, and back-side silver main grids and back-side aluminum fine grids are provided on the second SiN.sub.xH.sub.y layer; wherein the method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes comprises: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.P diffusion on the back side of the substrate.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on a front side of the substrate.fwdarw.deposition of a second SiN.sub.xH.sub.y preparatory layer on the back side of the substrate.fwdarw.UV laser ablation on the front side of the substrate and the back side of the substrate.fwdarw.screen printing; wherein the method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes comprises the following steps: A, preparation of an N-type double-sided cell before metallization: using an N-type monocrystalline silicon wafer as the substrate, forming the P-type doped region layer on a front side of the N-type monocrystalline silicon wafer successively by means of B diffusion, depositing the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer by means of PECVD, successively depositing the tunnel oxide layer and the polysilicon layer on a back side of the N-type monocrystalline silicon wafer by means of LPCVD, forming the N-type doped polysilicon layer by means of P diffusion, and depositing the second SiN.sub.xH.sub.y preparatory layer by means of PECVD; B, performing UV laser ablation on a front surface of a preparatory cell prepared by a step A to remove part of passivation dielectric film of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer; and performing UV laser ablation on a back side of the cell prepared by the step A to remove part of passivation dielectric film of the second SiN.sub.xH.sub.y preparatory layer; C, using aluminum paste to print and sinter a front surface of a preparatory cell prepared by a step B, so as to form a local contact point H-type front-side aluminum fine grid line electrode, wherein each of the front-side silver main grids is designed in a first segmented structure, the first segmented structure comprises a plurality of first g-id-grid segments, and the front-side silver main grids are distributed in aluminum fine grid lines; a number of the front-side aluminum fine grids is 106-122, each of the front-side aluminum fine grids has a width being 25-40 um and a height being 10-25 um; and each of the plurality of first grid segments of the front-side silver main grids has a length of 2-8 mm, a width of 0.1-2 mm and a height of 4-8 um, and a number of the front-side silver main grids is 5-12; and D, using weak burn-through type aluminum paste to print and sinter the back side of the preparatory cell prepared by the step B or the step C, so as to form a local contact point H-type back-side aluminum fine grid line electrode, wherein a number of the back-side aluminum fine grids is 110-160, each of the back-side aluminum fine grids has a width being 40-160 um and a height being 10-25 um; and each of the back-side silver main grids are designed in a second segmented structure, and the second segmented structure comprises a plurality of second grid segments; each of the plurality of second segmented structure grid segments has a length of 2-8 mm, a width of 0.1-2 mm and a height of 4-8 um, and a number of the back-side silver main grids is 5-12.

2. The preparation method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes as claimed in claim 1, wherein a thickness of the AlO.sub.x preparatory layer on the front side of the N-type substrate is 2-15 nm; a thickness of the first SiN.sub.xH.sub.y preparatory layer on the front side of the N-type substrate is 50-100 nm; a thickness of the tunnel oxide layer on the back side of the N-type substrate is 1-8 nm; a thickness of the N-type doped polysilicon layer on the back side of the N-type substrate is 100-200 nm; and a thickness of the second SiN.sub.xH.sub.y preparatory layer on the back side of the N-type substrate is 50-100 nm.

3. The preparation method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes as claimed in claim 1, wherein, in step B, a spot diameter of a UV laser is 10-30 um, and a space between two adjacent spots of the UV laser is 0-700 um; a front-side ablation film-removing depth is equal with thicknesses of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer; and a back-side ablation film-removing depth is equal with a thickness of the passivation dielectric film of the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate.

4. The method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes as claimed in claim 1, wherein the back-side aluminum fine grids and the N-type doped polysilicon layer form an ohmic contact.

5. The preparation method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes as claimed in claim 1, wherein, in step A, a AlO.sub.x preparatory layer on the front side of the N-type substrate with the thickness of 8 nm and first SiN.sub.xH.sub.y preparatory layer on the front side of the N-type substrate with the thickness of 80 nm are deposited by means of PECVD.

6. The preparation method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes as claimed in claim 1, wherein, in step A, a tunnel oxide layer on the back side of the N-type substrate with the thickness of 2 mm is deposited on a back side of the N-type silicon wafer successively by means of LPCVD; the N-type doped polysilicon layer on the back side of the N-type substrate with a thickness of 150 nm is formed by means of LPCVD and P diffusion; and second SiN.sub.xH.sub.y layer on the back side of the N-type substrate with a thickness of 75 nm is deposited by means of PECVD.

7. The preparation method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes as claimed in claim 1, wherein, in step C, the number of the front-side aluminum fine grids is 112, each of the front-side aluminum fine grids with the width being 32 um and each of the front-side aluminum fine grids the height being 18 um; and each segment of the front-side silver main grid has a length of 5 mm, a width of 1 mm and a height of 6 um, and the number of the front-side silver main grids is 8.

8. The preparation method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes as claimed in claim 1, wherein, in step D, a number of the back-side aluminum fine grids are 135, each of the back-side aluminum fine grids with the width being 100 um and each of the back-side aluminum fine grids with the height being 18 um; and the back-side silver main grids are designed in a segmented structure, each of the plurality of first grids segment has a length of 5 mm, a width of 1 mm and a height of 5 um, and a number of the back-side silver main grids are 8.

9. An N-type TOPCon cell with double-sided aluminum paste electrodes and prepared by the preparation method as claimed in claim 1, wherein a thickness of each of the front-side silver main grids is less than a thickness of each of the front-side aluminum fine grids, and the front-side silver main grids are distributed in the front-side aluminum fine grids; and a thickness of each of the back-side silver main grids is less than a thickness of each of the back-side aluminum fine grids, and the back-side silver main grids are distributed in the back-side aluminum fine grids; a number of the front-side aluminum fine grids is 106-122, each of the front-side aluminum fine grids has a width being 25-40 um and a height being 10-25 um; and each of the plurality of first grid segments of the front-side silver main grids has a length of 2-8 mm, a width of 0.1-2 mm and a height of 4-8 um, and a number of the front-side silver main grids is 5-12; a number of the back-side aluminum fine grids is 110-160, each of the back-side aluminum fine grids has a width being 40-160 um and a height being 10-25 um; and each of the back-side silver main grids are designed in a second segmented structure, and the second segmented structure comprises a plurality of second grid segments; each of the plurality of second grid segments has a length of 2-8 mm, a width of 0.1-2 mm and a height of 4-8 um, and a number of the back-side silver main grids is 5-12.

10. The N-type TOPCon cell as claimed in claim 9, wherein first contact grooves are provided on the AlO.sub.x layer and the first SiN.sub.xH.sub.y layer on the front side of the N-type substrate; and second contact grooves are provided on the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate.

11. The N-type TOPCon cell as claimed in claim 10, wherein the back-side aluminum fine grids pass through the second contact grooves to form second local contact points with the N-type doped polysilicon layer.

12. The N-type TOPCon cell as claimed in claim 9, wherein a thickness of the AlO.sub.x preparatory layer on the front side of the N-type substrate is 2-15 nm; a thickness of the first SiN.sub.xH.sub.y preparatory layer on the front side of the N-type substrate is 50-100 nm; a thickness of the tunnel oxide layer on the back side of the N-type substrate is 1-8 nm; a thickness of the N-type doped polysilicon layer on the back side of the N-type substrate is 100-200 nm; and a thickness of the second SiN.sub.xH.sub.y preparatory layer on the back side of the N-type substrate is 50-100 nm.

13. The N-type TOPCon cell as claimed in claim 9, wherein in step B of the preparation method for prepping the N-type TOPCon cell with double-sided aluminum paste electrodes, a spot diameter of a UV laser is 10-30 um, and a space between two adjacent spots of the UV laser is 0-700 um; a front-side ablation film-removing depth is equal with thicknesses of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer; and a back-side ablation film-removing depth is equal with a thickness of the passivation dielectric film of the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate.

14. The N-type TOPCon cell as claimed in claim 9, wherein the back-side aluminum fine grids and the N-type doped polysilicon layer form an ohmic contact.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a schematic diagram of a cell structure according to some embodiments of the present disclosure.

(2) FIG. 2 illustrates a schematic structural diagram of front-side grid lines of a cell according to some embodiments of the present disclosure.

(3) FIG. 3 illustrates a schematic structural diagram of back-side grid lines of a cell according to some embodiments of the present disclosure.

(4) In the drawings: 1, N-type substrate; 2, Front-side silver main grid; 3, Front-side aluminum fine grid; 4, Back-side silver main grid; 5, Back-side aluminum fine grid; 6, P-type doped region layer; 7, AlO.sub.x layer; 8, SiN.sub.xH.sub.y layer; 81, first SiN.sub.xH.sub.y layer; 82, second SiN.sub.xH.sub.y layer; 9, Tunnel oxide layer; 10, N-type doped polysilicon layer; 11, Local contact point; 111, first local contact points; 112, second local contact points.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(5) The present disclosure is further described below with reference to specific implementations.

General Embodiment

(6) As shown in FIGS. 1-3, an N-type TOPCon cell with double-sided aluminum paste electrodes includes an N-type substrate 1. A P-type doped region layer 6, an AlO.sub.x layer 7 and a first SiN.sub.xH.sub.y layer 81 are successively provided, from inside to outside, on a front side of the N-type substrate 1; a tunnel oxide layer 9, an N-type doped polysilicon layer 10 and a second SiN.sub.xH.sub.y layer 82 are successively provided, from inside to outside, on a back side of the N-type substrate 1; front-side silver main grids 2 and front-side aluminum fine grids 3 are provided on the first SiN.sub.xH.sub.y layer 81, and back-side silver main grids 4 and back-side aluminum fine grids 5 are provided on the second SiN.sub.xH.sub.y layer 82.

(7) A thickness of each of the front-side silver main grids 2 is less than a thickness of each of the front-side aluminum fine grids 3, and the front-side silver main grids 2 are distributed in the front-side aluminum fine grids 3; and a thickness of each of the back-side silver main grids 4 is less than a thickness of each of the back-side aluminum fine grids 5, and the back-side silver main grids 4 are distributed in the back-side aluminum fine grids 5. First contact grooves are provided on the AlO.sub.x layer 7 and the first SiN.sub.xH.sub.y layer 81 on the front side of the N-type substrate 1; and second contact grooves are provided on the second SiN.sub.xH.sub.y layer 82 on the back side of the N-type substrate 1. The front-side aluminum fine grids 3 pass through the first contact grooves to form first local contact points 111 with the AlO.sub.x layer 7. The back-side aluminum fine grids 5 pass through the second contact grooves to form second local contact points 112 with the N-type doped polysilicon layer 10.

(8) A method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes includes the following processes: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.P diffusion on the back side of the substrate.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on a front side of the substrate.fwdarw.deposition of a second SiN.sub.xH.sub.y preparatory layer on the back side of the substrate.fwdarw.UV laser ablation on the front side of the substrate and the back side of the substrate.fwdarw.screen printing. The method includes the following specific preparation steps.

(9) At step A, namely the step of preparation of an N-type double-sided cell before metallization: an N-type monocrystalline silicon wafer as the substrate, the P-type doped region layer is formed on a front side of the N-type monocrystalline silicon wafer successively by means of B diffusion, the AlO.sub.x preparatory layer on the front side of the N-type substrate 1 with the thickness of 2-15 nm and the first SiN.sub.xH.sub.y preparatory layer on the front side of the N-type substrate 1 with the thickness of 50-100 nm are deposited by means of PECVD, a tunnel oxide layer on the back side of the N-type substrate 1 with the thickness of 1-8 mm is deposited on a back side of the N-type silicon wafer by means of LPCVD; and the N-type doped polysilicon layer on the back side of the N-type substrate 1 with a thickness of 100-200 nm is formed by means of LPCVD and P diffusion; and the second SiN.sub.xH.sub.y preparatory layer on the back side of the N-type substrate 1 with a thickness of 50-100 nm is deposited by means of PECVD.

(10) A preparation cell before metallization means before the screen printing of a method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes.

(11) At step B, UV laser ablation is performed on a front surface of a preparatory cell prepared by a step A to remove part of passivation dielectric film of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer; and UV laser ablation is performed on a back side of the cell prepared by the step A to remove part of passivation dielectric film of the second SiN.sub.xH.sub.y preparatory layer. A spot diameter of a UV laser is 10-30 um, and a space between two adjacent of spots of the UV laser is 0-700 um; a front-side ablation film-removing depth is consistent with thicknesses of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer; and a back-side ablation film-removing depth is consistent with a thickness of the passivation dielectric film of the second SiN.sub.xH.sub.y layer 82 on the back side of the N-type substrate 1.

(12) At step C, aluminum paste (Al 60-80 wt %, Si40 wt %, glass powder5 wt %, and resin5 wt %; and an organic solvent is added to the aluminum paste adjust viscosity to be 20-25 Pa.Math.s) is used to print and sinter the front surface of the cell by the step B, so as to form a local contact point H-type front-side aluminum fine grids line electrode, where each of a front-side silver main grids are designed in a first segmented structure, the first segmented structure includes a plurality of first grid segments, and each of a front-side silver main grids is distributed in aluminum fine grid lines; a number of the front-side aluminum fine grids is 106-122, each of the front-side aluminum fine grids has a width being 25-40 um and each of the front-side aluminum fine grids has a height being 10-25 um; and each of the plurality of first grid segments of the front-side silver main grids has a length of 2-8 mm, a width of 0.1-2 mm and a height of 4-8 um, and a number of the front-side silver main grids is 5-12.

(13) At step D, weak burn-through type aluminum paste (Al 60-80 wt %, Si40 wt %, glass powder5 wt %, and resin5 wt %; and the organic solvent is added to the weak burn-through type aluminum paste adjust the viscosity to be 20-25 Pa.Math.s) is used to print and sinter a back side of the cell by the step B or step C, so as to form a local contact point H-type back-side aluminum fine grids line electrode, where a number of the back-side aluminum fine grids is 110-160, with each of the back-side aluminum fine grids has a width being 40-160 um and each of the back-side aluminum fine grids the height being 10-25 um; and each of the back-side silver main grids are designed in a second segmented structure, and the second segmented structure includes a plurality of second grid segments; each of the plurality of second grid segments has a length of 2-8 mm, a width of 0.1-2 mm and a height of 4-8 um, and a number of the back-side silver main grids is 5-12. The aluminum fine grids formed on the back side by means of sintering forms an ohmic contact with the N-type doped polysilicon layer, without forming a BSF layer.

Embodiment 1

(14) As shown in FIG. 1, an N-type TOPCon cell with double-sided aluminum paste electrodes includes an N-type substrate 1. A P-type doped region layer 6, an AlO.sub.x layer 7 and a first SiN.sub.xH.sub.y layer 81 are successively provided, from inside to outside, on a front side of the N-type substrate 1; a tunnel oxide layer 9, an N-type doped polysilicon layer 10 and a second SiN.sub.xH.sub.y layer 82 are successively provided, from inside to outside, on a back side of the N-type substrate 1; as shown in FIG. 2, front-side silver main grids 2 and front-side aluminum fine grids 3 are provided on the first SiN.sub.xH.sub.y layer 81; and as shown in FIG. 3, back-side silver main grids 4 and back-side aluminum fine grids 5 are provided on the second SiN.sub.xH.sub.y layer 82.

(15) A thickness of each of the front-side silver main grids 2 is less than a thickness of each of the front-side aluminum fine grids 3, and the front-side silver main grids 2 are distributed in the front-side aluminum fine grids 3; and a thickness of each of the back-side silver main grids 4 is less than a thickness of each of the back-side aluminum fine grids 5, and the back-side silver main grids 4 are distributed in the back-side aluminum fine grids 5. First contact grooves are provided on the AlO.sub.x layer 7 and the first SiN.sub.xH.sub.y layer 81 on the front side of the N-type substrate 1; and second contact grooves are provided on the second SiN.sub.xH.sub.y layer 82 on the back side of the N-type substrate 1. The front-side aluminum fine grids 3 pass through the first contact grooves to form first local contact points 111 with the AlO.sub.x layer 7. The back-side aluminum fine grids 5 pass through the second contact grooves to form second local contact points 112 with the N-type doped polysilicon layer 10.

(16) A method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes includes the following processes: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on a front side of the substrate.fwdarw.deposition of a second SiN.sub.xH.sub.y preparatory layer on the back side of the substrate.fwdarw.UV laser ablation on the front side of the substrate and the back side of the substrate.fwdarw.screen printing. The method specifically includes the following steps.

(17) At step A, namely the step of preparation of an N-type double-sided cell before metallization: an N-type monocrystalline silicon wafer as the substrate, the P-type doped region layer is formed on a front side of the N-type monocrystalline silicon wafer successively by means of B diffusion, a AlO.sub.x layer on the front side of the N-type substrate 1 with the thickness of 8 nm and first SiN.sub.xH.sub.y layer on the front side of the N-type substrate 1 with the thickness of 80 nm are deposited by means of PECVD, a tunnel oxide layer on the back side of the N-type substrate 1 with the thickness of 2 mm is deposited on a back side of the N-type silicon wafer by means of LPCVD; and the N-type doped polysilicon layer on the back side of the N-type substrate with a thickness of 150 nm is formed by means of LPCVD and P diffusion; and second SiN.sub.xH.sub.y preparatory layer on the back side of the N-type substrate 1 with a thickness of 75 nm is deposited by means of PECVD.

(18) At step B, UV laser ablation is performed on a front surface of a preparatory cell prepared by a step A to remove part of passivation dielectric film of the AlO.sub.x preparatory layer and an SiN.sub.xH.sub.y preparatory layer; and UV laser ablation is performed on a back side of the cell prepared by the step A to remove part of passivation dielectric film of the second SiN.sub.xH.sub.y preparatory layer. A spot diameter of a UV laser is 20 um, and a space between two adjacent of spots of the UV laser is 350 um; a front-side ablation film-removing depth is consistent with thicknesses of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer 81; and a back-side ablation film-removing depth is consistent with a thickness of the passivation dielectric film of the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate 1.

(19) At step C, aluminum paste (Al 65 wt %, Si 25 wt %, glass powder 5 wt %, and resin 5 wt %; and an organic solvent is added to the aluminum paste adjust viscosity to be 20 Pa.Math.s) is used to print and sinter the front surface of the cell by the step B, so as to form a local contact point H-type front-side aluminum fine grids line electrode, where each of a front-side silver main grids are designed in a first segmented structure, the first segmented structure includes a plurality of first grid segments, and each of a front-side silver main grids is distributed in aluminum fine grid lines; a number of the front-side aluminum fine grids is 112, each of the front-side aluminum fine grids has a the width being 32 um and each of the front-side aluminum fine grids has a height being 18 um; and each of the plurality of first grid segments of the front-side silver main grids has a length of 5 mm, a width of 1 mm and a height of 6 um, and a number of the front-side silver main grids is 8.

(20) At step D, weak burn-through type aluminum paste (Al 65 wt %, Si 25 wt %, glass powder 5 wt %, and resin 5 wt %; and the organic solvent is added to the weak burn-through type aluminum paste adjust the viscosity to be 20 Pa.Math.s) is used to print and sinter a back side of the cell by the step B or step C, so as to form a local contact point H-type back-side aluminum fine grid line electrode, where a number of the back-side aluminum fine grids is 135, each of the back-side aluminum fine grids with the width being 100 um and each of the back-side aluminum fine grids with the height being 18 um; and each of the back-side silver main grids are designed in a second segmented structure, and the second segmented structure includes a plurality of second grid segments; each of the plurality of first grid segments has a length of 5 mm, a width of 1 mm and a height of 5 um, and a number of the back-side silver main grids is 8. The aluminum fine grids formed on the back side by means of sintering forms an ohmic contact with the N-type doped polysilicon layer, without forming a BSF layer.

Embodiment 2

(21) As shown in FIG. 1, an N-type TOPCon cell with double-sided aluminum paste electrodes includes an N-type substrate 1. A P-type doped region layer 6, an AlO.sub.x layer 7 and a first SiN.sub.xH.sub.y layer 81 are successively provided, from inside to outside, on a front side of the N-type substrate 1; a tunnel oxide layer 9, an N-type doped polysilicon layer 10 and a second SiN.sub.xH.sub.y layer 82 are successively provided, from inside to outside, on a back side of the N-type substrate 1; as shown in FIG. 2, front-side silver main grids 2 and front-side aluminum fine grids 3 are provided on the first SiN.sub.xH.sub.y layer 81; and as shown in FIG. 3, back-side silver main grids 4 and back-side aluminum fine grids 5 are provided on the second SiN.sub.xH.sub.y layer 82.

(22) A thickness of each of the front-side silver main grids 2 is less than a thickness of each of the front-side aluminum fine grids 3, and the front-side silver main grids 2 are distributed in the front-side aluminum fine grids 3; and a thickness of each of the back-side silver main grids 4 is less than a thickness of each of the back-side aluminum fine grids 5, and the back-side silver main grids 4 are distributed in the back-side aluminum fine grids 5. First contact grooves are provided on the first AlO.sub.x layer 7 and the first SiN.sub.xH.sub.y layer 81 on the front side of the N-type substrate 1; and second contact grooves are provided on the second SiN.sub.xH.sub.y layer 82 on the back side of the N-type substrate 1. The front-side aluminum fine grids 3 pass through the first contact grooves to form first local contact points 111 with the AlO.sub.x layer 7. The back-side aluminum fine grids 5 pass through the second contact grooves to form second local contact points 112 with the N-type doped polysilicon layer 10.

(23) A method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes includes the following processes: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and N-type doped a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.P diffusion on the back side of the substrate.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on a front side of the substrate.fwdarw.deposition of a second SiN.sub.xH.sub.y preparatory layer on the back side of the substrate.fwdarw.UV laser ablation on the front side of the substrate and the back side of the substrate.fwdarw.screen printing. The method includes the following specific preparation steps.

(24) At step A, namely the step of preparation of an N-type double-sided cell before metallization: an N-type monocrystalline silicon wafer as the substrate, the P-type doped region layer is formed on a front side of the N-type monocrystalline silicon wafer successively by means of B diffusion, a AlO.sub.x preparatory layer on the front side of the N-type substrate 1 with the thickness of 15 nm and first SiN.sub.xH.sub.y layer on the front side of the N-type substrate 1 with the thickness of 50 nm and the thickness of 100 nm are deposited by means of PECVD, a tunnel oxide layer on the back side of the N-type substrate 1 with the thickness of 1 mm is deposited on a back side of the N-type silicon wafer by means of LPCVD; and the N-type doped polysilicon layer on the back side of the N-type substrate with a thickness of 200 nm is formed by means of LPCVD and P diffusion; and the second SiN.sub.xH.sub.y preparatory layer on the back side of the N-type substrate 1 with a thickness of 100 nm is deposited by means of PECVD.

(25) At step B, UV laser ablation is performed on a front surface of a preparatory cell prepared by a step A to remove part of passivation dielectric film of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer; and UV laser ablation is performed on a back side of the cell prepared by the step A to remove part of passivation dielectric film of the second SiN.sub.xH.sub.y layer. A spot diameter of a UV laser is 10 um, and a space between two adjacent of spots of the UV laser is 700 um; a front-side ablation film-removing depth is consistent with thicknesses of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y layer 81; and a back-side ablation film-removing depth is consistent with a thickness of the passivation dielectric film of the second SiN.sub.xH.sub.y layer 82 on the back side of the N-type substrate 1.

(26) At step C, aluminum paste (Al 65 wt %, Si 25 wt %, glass powder 5 wt %, and resin 5 wt %; and an organic solvent is added to the aluminum paste adjust viscosity to be 20 Pa.Math.s) is used to print and sinter the front surface of the cell by the step B, so as to form a local contact point H-type front-side aluminum fine grid line electrode, where each of a front-side silver main grids are designed in a first segmented structure, the first segmented structure includes a plurality of first grid segments, and each of a front-side silver main grids is distributed in aluminum fine grid lines; a number of the front-side aluminum fine grids is 106, each of the front-side aluminum fine grids with the width being 40 um and each of the front-side aluminum fine grids the height being 10 um; and each of the plurality of first grid segments of the front-side silver main grids has a length of 8 mm, a width of 0.1 mm and a height of 8 um, and a number of the front-side silver main grids is 5.

(27) At step D, weak burn-through type aluminum paste (Al 65 wt %, Si 25 wt %, glass powder 5 wt %, and resin 5 wt %; and the organic solvent is added to the weak burn-through type aluminum paste adjust the viscosity to be 20 Pa.Math.s) is used to print and sinter a back side of the cell by the step B or step C, so as to form a local contact point H-type back-side aluminum fine grids line electrode, where a number of the back-side aluminum fine grids is 110, each of the back-side aluminum fine grids width being 160 um and each of the back-side aluminum fine grids the height being 10 um; and the back-side silver main grids are designed in a second segmented structure, and the second segmented structure includes a plurality of second grid segments; each of the plurality of second grid segments has a length of 8 mm, a width of 0.1 mm and a height of 8 um, and a number of the back-side silver main grids is 5. The aluminum fine grid formed on the back side by means of sintering forms an ohmic contact with the N-type doped polysilicon layer, without forming a BSF layer.

Embodiment 3

(28) As shown in FIGS. 1-3, an N-type TOPCon cell with double-sided aluminum paste electrodes includes an N-type substrate 1. A P-type doped region layer 6, an AlO.sub.x layer 7 and a first SiN.sub.xH.sub.y layer 81 are successively provided, from inside to outside, on a front side of the N-type substrate 1; a tunnel oxide layer 9, an N-type doped polysilicon layer 10 and a second SiN.sub.xH.sub.y layer 82 are successively provided, from inside to outside, on a back side of the N-type substrate 1; and front-side silver main grids 2 and front-side aluminum fine grids 3 are provided on the first SiN.sub.xH.sub.y layer 81, and back-side silver main grids 4 and back-side aluminum fine grids 5 are provided on the second SiN.sub.xH.sub.y layer 82.

(29) A thickness of each of the front-side silver main grids 2 is less than a thickness of each of the front-side aluminum fine grids 3, and the front-side silver main grids 2 are distributed in the front-side aluminum fine grids 3; and a thickness of each of the back-side silver main grids 4 is less than a thickness of each of the back-side aluminum fine grids 5, and the back-side silver main grids 4 are distributed in the back-side aluminum fine grids 5. First contact grooves are provided on the AlO.sub.x layer 7 and the first SiN.sub.xH.sub.y layer 81 on the front side of the N-type substrate 1; and second contact grooves are provided on the second SiN.sub.xH.sub.y layer 82 on the back side of the N-type substrate 1. The front-side aluminum fine grids 3 pass through the first contact grooves to form first local contact points 111 with the AlO.sub.x layer 7. The back-side aluminum fine grids 5 pass through the second contact grooves to form second local contact points 112 with the N-type doped polysilicon layer 10.

(30) A method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes includes the following processes: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and N-type doped a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.P diffusion on the back side of the substrate.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on a front side of the substrate.fwdarw.deposition of a second SiN.sub.xH.sub.y preparatory layer on the back side of the substrate.fwdarw.UV laser ablation on the front side of the substrate and the back side of the substrate.fwdarw.screen printing. The method specifically includes the following steps.

(31) At step A, namely the step of preparation of an N-type double-sided cell before metallization: an N-type monocrystalline silicon wafer as the substrate, the P-type doped region layer is formed on a front side of the N-type monocrystalline silicon wafer successively by means of B diffusion, a AlO.sub.x layer on the front side of the N-type substrate 1 with the thickness of 2 nm and first SiN.sub.xH.sub.y layer on the front side of the N-type substrate 1 with the thickness of 50 nm are deposited by means of PECVD, a tunnel oxide layer on the back side of the N-type substrate 1 with the thickness of 8 mm is deposited on a back side of the N-type silicon wafer by means of LPCVD; and the N-type doped polysilicon layer on the back side of the N-type substrate with a thickness of 100 nm is formed by means of LPCVD and P diffusion; and the second SiN.sub.xH.sub.y preparatory layer on the back side of the N-type substrate 1 with a thickness of 60 nm is deposited by means of PECVD.

(32) At step B, UV laser ablation is performed on a front surface of a preparatory the cell prepared by a step A to remove part of passivation dielectric film of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer; and UV laser ablation is performed on a back side of the cell prepared by the step A to remove part of passivation dielectric film of the second SiN.sub.xH.sub.y preparatory layer. A spot diameter of a UV laser is 30 um, and a space between two adjacent of spots of the UV laser is 0 um; a front-side ablation film-removing depth is consistent with the thicknesses of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer; and a back-side ablation film-removing depth is consistent with a thickness of the passivation dielectric film of the second SiN.sub.xH.sub.y layer 82 on the back side of the N-type substrate 1.

(33) At step C, aluminum paste (Al 65 wt %, Si 25 wt %, glass powder 5 wt %, and resin 5 wt %; and an organic solvent is added to the aluminum paste adjust viscosity to be 20 Pa.Math.s) is used to print and sinter the front surface of the cell by the step B, so as to form a local contact point H-type front-side aluminum fine grids line electrode, where each of a front-side silver main grids are designed in a first segmented structure, the first segmented structure includes a plurality of first grid segments, and each of a front-side silver main grids is distributed in aluminum fine grid lines; a number of the front-side aluminum fine grids is 122, each of the front-side aluminum fine grids with the width being 25 um and each of the front-side aluminum fine grids the height being 25 um; and each of the plurality of first grid segments of the front-side silver main grid has a length of 2 mm, a width of 2 mm and a height of 4 um, and a number of the front-side silver main grids is 12.

(34) At step D, weak burn-through type aluminum paste (Al 65 wt %, Si 25 wt %, glass powder 5 wt %, and resin 5 wt %; and the organic solvent is added to the weak burn-through type aluminum paste adjust the viscosity to be 20 Pa.Math.s) is used to print and sinter a back side of the cell by the step B or step C, so as to form a local contact point H-type back-side aluminum fine grid line electrode, where a number of the back-side aluminum fine grids is 160, with each of the back-side aluminum fine grids the width being 40 um and each of the back-side aluminum fine grids with the height being 10 um; and each of the back-side silver main grids are designed in a second grid segmented structure, each of the plurality of second grid segments has a length of 8 mm, a width of 0.1 mm and a height of 8 um, and a number of the back-side silver main grids is 12. The aluminum fine grids formed on the back side by means of sintering forms an ohmic contact with the N-type doped polysilicon layer, without forming a BSF layer.

Embodiment 4

(35) As shown in FIG. 1, an N-type TOPCon cell with double-sided aluminum paste electrodes includes an N-type substrate 1. A P-type doped region layer 6, an AlO.sub.x layer 7 and a first SiN.sub.xH.sub.y layer 81 are successively provided, from inside to outside, on a front side of the N-type substrate 1; a tunnel oxide layer 9, an N-type doped polysilicon layer 10 and a second SiN.sub.xH.sub.y layer 82 are successively provided, from inside to outside, on a back side of the N-type substrate 1; as shown in FIG. 2, front-side silver main grids 2 and front-side aluminum fine grids 3 are provided on the first SiN.sub.xH.sub.y layer 81; and as shown in FIG. 3, back-side silver main grids 4 and back-side aluminum fine grids 5 are provided on the second SiN.sub.xH.sub.y layer 82.

(36) A thickness of each of the front-side silver main grids 2 is less than a thickness of each of the front-side aluminum fine grids 3, and the front-side silver main grids 2 are distributed in the front-side aluminum fine grids 3; and a thickness of each of the back-side silver main grids 4 is less than a thickness of each of the back-side aluminum fine grids 5, and the back-side silver main grids 4 are distributed in the back-side aluminum fine grids 5. First contact grooves are provided on the AlO.sub.x layer 7 and the first SiN.sub.xH.sub.y layer 81 on the front side of the N-type substrate 1; and second contact groove is provided on the second SiN.sub.xH.sub.y layer 82 on the back side of the N-type substrate 1. The front-side aluminum fine grids 3 pass through the first contact grooves to form first local contact points 111 with the AlO.sub.x layer 7. The back-side aluminum fine grids 5 pass through the second contact grooves to form second local contact points 112 with the N-type doped polysilicon layer 10.

(37) A method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes includes the following processes: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and N-type doped a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.P diffusion on the back side of the substrate.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on a front side of the substrate.fwdarw.deposition of a second SiN.sub.xH.sub.y preparatory layer on the back side of the substrate.fwdarw.UV laser ablation on the front side of the substrate and the back side of the substrate.fwdarw.screen printing. The method specifically includes the following steps.

(38) At step A, namely the step of preparation of an N-type double-sided cell before metallization: an N-type monocrystalline silicon wafer as the substrate, the P-type doped region layer is formed on a front side of the N-type monocrystalline silicon wafer successively by means of B diffusion, the AlO.sub.x preparatory layer on the front side of the N-type substrate 1 with the thickness of 4 nm and first SiN.sub.xH.sub.y preparatory layer on the front side of the N-type substrate 1 with the thickness of 60 nm are deposited by means of PECVD, a tunnel oxide layer on the back side of the N-type substrate 1 with the thickness of 2 mm is deposited on the back side of the N-type silicon wafer by means of LPCVD; and the N-type doped polysilicon layer on the back side of the N-type substrate 1 with the thickness of 120 nm is formed by means of LPCVD and P diffusion; and the second SiN.sub.xH.sub.y preparatory layer on the back side of the N-type substrate 1 with the thickness of 80 nm is deposited by means of PECVD.

(39) At step B, UV laser ablation is performed on a front surface of a preparatory cell prepared by a step A to remove part of passivation dielectric film of the AlO.sub.x preparatory layer and an SiN.sub.xH.sub.y preparatory layer; and UV laser ablation is performed on a back side of the cell prepared by the step A to remove part of passivation dielectric film of the second SiN.sub.xH.sub.y preparatory layer. A spot diameter of a UV laser is 25 um, and a space between two adjacent of spots of the UV laser is 100 um; a front-side ablation film-removing depth is consistent with the thicknesses of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer 81; and a back-side ablation film-removing depth is consistent with a thickness of the passivation dielectric film of the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate 1.

(40) At step C, aluminum paste (Al 65 wt %, Si 25 wt %, glass powder 5 wt %, and resin 5 wt %; and an organic solvent is added to the aluminum paste adjust viscosity to be 20 Pa.Math.s) is used to print and sinter the front surface of the cell by the step B, so as to form a local contact point H-type front-side aluminum fine grid line electrode, where each of a front-side silver main grids are designed in a first segmented structure, the first segmented structure includes a plurality of first grid segments, and each of a front-side silver main grids is distributed in aluminum fine grid lines; a number of the front-side aluminum fine grids is 112, each of the front-side aluminum fine grids with the width being 30 um and each of the front-side aluminum fine grids the height being 20 um; and each segment of the front-side silver main grid has a length of 4 mm, a width of 0.5 mm and a height of 5 um, and a number of the front-side silver main grids is 7.

(41) At step D, weak burn-through type aluminum paste (Al 65 wt %, Si 25 wt %, glass powder 5 wt %, and resin 5 wt %; and the organic solvent is added to the weak burn-through type aluminum paste adjust the viscosity to be 20 Pa.Math.s) is used to print and sinter a back side of the cell by the step B or step C, so as to form a local contact point H-type back-side aluminum fine grids line electrode, where a number of the back-side aluminum fine grids is 125, with each of the back-side aluminum fine grids width being 55 um and each of the back-side aluminum fine grids the height being 15 um; and each of the back-side silver main grids are designed in a second segmented structure, and the second segmented structure includes a plurality of second grid segments; each of the plurality of second grid segments has a length of 4 mm, a width of 0.8 mm and a height of 5 um, and a number of the back-side silver main grids is 7. The aluminum fine grids formed on the back side by means of sintering forms an ohmic contact with the N-type doped polysilicon layer, without forming a BSF layer.

Embodiment 5

(42) As shown in FIG. 1, an N-type TOPCon cell with double-sided aluminum paste electrodes includes an N-type substrate 1. A P-type doped region layer 6, an AlO.sub.x layer 7 and a first SiN.sub.xH.sub.y layer 81 are successively provided, from inside to outside, on a front side of the N-type substrate 1; a tunnel oxide layer 9, an N-type doped polysilicon layer 10 and a second SiN.sub.xH.sub.y layer 82 are successively provided, from inside to outside, on a back side of the N-type substrate 1; as shown in FIG. 2, front-side silver main grids 2 and front-side aluminum fine grids 3 are provided on the first SiN.sub.xH.sub.y layer 81; and as shown in FIG. 3, back-side silver main grids 4 and back-side aluminum fine grids 5 are provided on the second SiN.sub.xH.sub.y layer 82.

(43) A thickness of each of the front-side silver main grids 2 is less than a thickness of each of the front-side aluminum fine grids 3, and the front-side silver main grids 2 are distributed in the front-side aluminum fine grids 3; and a thickness of each of the back-side silver main grids 4 is less than a thickness of each of the back-side aluminum fine grids 5, and the back-side silver main grids 4 are distributed in the back-side aluminum fine grids 5. First contact grooves are provided on the AlO.sub.x layer 7 and the first SiN.sub.xH.sub.y layer 81 on the front side of the N-type substrate 1; and second contact grooves are provided on the second SiN.sub.xH.sub.y layer 82 on the back side of the N-type substrate 1. The front-side aluminum fine grids 3 pass through the first contact grooves to form first local contact points 111 with the AlO.sub.x layer 7. The back-side aluminum fine grids 5 pass through the second contact grooves to form second local contact points 112 with the N-type doped polysilicon layer 10.

(44) A method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes includes the following processes: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and N-type doped a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.P diffusion on the back side of the substrate.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on a front side of the substrate.fwdarw.deposition of a second SiN.sub.xH.sub.y preparatory layer on the back side of the substrate.fwdarw.UV laser ablation on the front side of the substrate and the back side of the substrate.fwdarw.screen printing. The method specifically includes the following steps.

(45) At step A, namely the step of preparation of an N-type double-sided cell before metallization: an N-type monocrystalline silicon wafer as the substrate, the P-type doped region layer is formed on a front side of the N-type monocrystalline silicon wafer successively by means of B diffusion, the AlO.sub.x preparatory layer on the front side of the N-type substrate 1 with the thickness of 12 nm and first SiN.sub.xH.sub.y preparatory layer on the front side of the N-type substrate 1 with the thickness of 90 nm are deposited by means of PECVD, the tunnel oxide layer on the back side of the N-type substrate 1 with the thickness of 3 mm is deposited on the back side of the N-type silicon wafer by means of LPCVD; and the N-type doped polysilicon layer on the back side of the N-type substrate with a thickness of 180 nm is formed by means of LPCVD and P diffusion; and the second SiN.sub.xH.sub.y preparatory layer on the back side of the N-type substrate 1 with the thickness of 90 nm is deposited by means of PECVD.

(46) At step B, UV laser ablation is performed on the front surface of a preparatory cell prepared by a step A to remove part of passivation dielectric film of the AlO.sub.x preparatory layer and an SiN.sub.xH.sub.y preparatory layer; and UV laser ablation is performed on a back side of the cell prepared by the step A to remove part of passivation dielectric film of the second SiN.sub.xH.sub.y preparatory layer. A spot diameter of a UV laser is 15 um, and a space between two adjacent of spots of the UV laser is 650 um; a front-side ablation film-removing depth is consistent with thicknesses of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer; and a back-side ablation film-removing depth is consistent with a thickness of the passivation dielectric film of the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate 1.

(47) At step C, aluminum paste (Al 65 wt %, Si 25 wt %, glass powder 5 wt %, and resin 5 wt %; and an organic solvent is added to the aluminum paste adjust viscosity to be 20 Pa.Math.s) is used to print and sinter the front surface of the cell by the step B, so as to form a local contact point H-type front-side aluminum fine grid line electrode, where each of the front-side silver main grids are designed in a first segmented structure, the first segmented structure includes a plurality of first grid segments, and each of a front-side silver main grids is distributed in aluminum fine grid lines; a number of the front-side aluminum fine grids is 120, each of the front-side aluminum fine grids with the width being 35 um and each of the front-side aluminum fine grids the height being 22 um; and each of the plurality of first grid segments of the front-side silver main grid has a length of 6 mm, a width of 1.6 mm and a height of 6.5 um, and a number of the front-side silver main grids is 10.

(48) At step D, weak burn-through type aluminum paste (Al 65 wt %, Si 25 wt %, glass powder 5 wt %, and resin 5 wt %; and the organic solvent is added to the weak burn-through type aluminum paste adjust the viscosity to be 20 Pa.Math.s) is used to print and sinter a back side of the cell by the step B or step C, so as to form a local contact point H-type back-side aluminum fine grid line electrode, where a number of the back-side aluminum fine grids is 150, each of the back-side aluminum fine grids with the width being 150 um and each of the back-side aluminum fine grids with the height being 15 um; and the back-side silver main grids are designed in a second segmented structure, and the second segmented structure includes a plurality of second grid segments; each of the plurality of second grid segments has a length of 6.5 mm, a width of 1.8 mm and a height of 6 um, and a number of the back-side silver main grids is 10. The aluminum fine grids formed on the back side by means of sintering forms an ohmic contact with the N-type doped polysilicon layer, without forming a BSF layer.

(49) Comparative embodiment 1 (the difference between this comparative example and Embodiment 1 lies in that the front side of the substrate and the back side are not provided with aluminum grids line.)

(50) An N-type TOPCon cell includes an N-type substrate 1. A P-type doped region layer 6, an AlO.sub.x layer 7 and a first SiN.sub.xH.sub.y layer 81 are successively provided, from inside to outside, on a front side of the N-type substrate 1; a tunnel oxide layer 9, an N-type doped polysilicon layer 10 and a second SiN.sub.xH.sub.y layer 82 are successively provided, from inside to outside, on a back side of the N-type substrate 1; and front-side silver main grids 2 is provided on the first SiN.sub.xH.sub.y layer 81, and back-side silver main grids 4 are provided on the second SiN.sub.xH.sub.y layer 82.

(51) A method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes includes the following processes: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and N-type doped a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.P diffusion on the back side of a substrate.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on a front side of the substrate.fwdarw.deposition of a second SiN.sub.xH.sub.y preparatory layer on the back side of the substrate.fwdarw.UV laser ablation on the front side of the substrate and the back side of the substrate.fwdarw.screen printing. The preparation process specifically includes the following steps.

(52) At step A, namely the step of preparation of an N-type double-sided cell before metallization: an N-type monocrystalline silicon wafer as the substrate, the P-type doped region layer is formed on a front side of the N-type monocrystalline silicon wafer successively by means of B diffusion, a AlO.sub.x preparatory layer on the front side of the N-type substrate 1 with the thickness of 8 nm and the first SiN.sub.xH.sub.y preparatory layer on the front side of the N-type substrate 1 with the thickness of 80 nm are deposited by means of PECVD, a tunnel oxide layer on the back side of the N-type substrate 1 with the thickness of 4 mm is deposited on a back side of the N-type silicon wafer by means of LPCVD; and the N-type doped polysilicon layer on the back side of the N-type substrate 1 with a thickness of 150 nm is formed by means of LPCVD and P diffusion; and the second SiN.sub.xH.sub.y preparatory layer on the back side of the N-type substrate 1 with a thickness of 75 nm is deposited by means of PECVD.

(53) At step B, UV laser ablation is performed on a front surface of a preparatory cell prepared by a step A to remove part of passivation dielectric film of the AlO.sub.x preparatory layer and an the first SiN.sub.xH.sub.y preparatory layer; and UV laser ablation is performed on a back side of the cell prepared by the step A to remove part of passivation dielectric film of the second SiN.sub.xH.sub.y preparatory layer.

(54) At step C, aluminum paste is used to print and sinter the front surface of the cell by the step B, so as to form a local contact point H-type front-side aluminum fine grids line electrode, where each of the front-side silver main grids are designed in a first segmented structure, the first segmented structure includes a plurality of first grid segments; and each of the plurality of first grid segments of the front-side silver main grids has a length of 5 mm, each of the plurality of first grid segments of the front-side silver main grids has a width of 1 mm and each of the plurality of first grid segments of the front-side silver main grids has a height of 6 um, and a number of the front-side silver main grids is 8.

(55) At step D, each of the back-side silver main grids are designed in a second segmented structure, and the second segmented structure includes a plurality of second grid segments; and each of the plurality of second grid segments has a length of 5 mm, a width of 1 mm and a height of 5 um, and a number of the front-side silver main grids is 8.

(56) Comparative embodiment 2 (the difference between this comparative embodiment and Embodiment 1 lies in that UV laser ablation is not used on the front side of the cell to remove part of the AlO.sub.x layer and an SiN.sub.xH.sub.y layer passivation dielectric film, and is also not used on the back side of the cell to remove part of the SiN.sub.xH.sub.y layer passivation dielectric film.)

(57) An N-type TOPCon cell includes an N-type substrate 1. A P-type doped region layer 6, an AlO.sub.x layer 7 and a first SiN.sub.xH.sub.y layer 81 are successively provided, from inside to outside, on a front side of the N-type substrate 1; a tunnel oxide layer 9, an N-type doped polysilicon layer 10 and a second SiN.sub.xH.sub.y layer 82 are successively provided, from inside to outside, on a back side of the N-type substrate 1; and front-side silver main grids 2 and front-side aluminum fine grids 3 are provided on the first SiN.sub.xH.sub.y layer 81, and back-side silver main grids 4 and back-side aluminum fine grids 5 are provided on the second SiN.sub.xH.sub.y layer 82.

(58) A thickness of each of the front-side silver main grids 2 is less than a thickness of each of the front-side aluminum fine grids 3, and the front-side silver main grids 2 are distributed in the front-side aluminum fine grids 3; and a thickness of each of the back-side silver main grids 4 is less than a thickness of each of the back-side aluminum fine grids 5, and the back-side silver main grids 4 are distributed in the back-side aluminum fine grids 5. First contact grooves are provided on the AlO.sub.x layer 7 and the first SiN.sub.xH.sub.y layer 8 on the front side of the N-type substrate 1; and second contact grooves are provided on the second SiN.sub.xH.sub.y layer 82 on the back side of the N-type substrate 1. The front-side aluminum fine grids 3 pass through the first contact grooves to form first local contact points 111 with the AlO.sub.x layer 7. The back-side aluminum fine grids 5 pass through the second contact grooves to form second local contact points 112 with the N-type doped polysilicon layer 10.

(59) A method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes includes the following processes: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and N-type doped a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.P diffusion on the back side of the substrate.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on a front side of the substrate.fwdarw.deposition of a second SiN.sub.xH.sub.y preparatory layer on the back side of the substrate.fwdarw.screen printing. The preparation process specifically includes the following steps.

(60) At step A, namely the step of preparation of an N-type double-sided cell before metallization: an N-type monocrystalline silicon wafer is used as the substrate, the P-type doped region layer is formed on a front side of the N-type monocrystalline silicon wafer successively by means of B diffusion, a AlO.sub.x layer on the front side of the N-type substrate 1 with the thickness of 8 nm and first SiN.sub.xH.sub.y layer on the front side of the N-type substrate 1 with the thickness of 80 nm are deposited by means of PECVD, a tunnel oxide layer on the back side of the N-type substrate 1 with the thickness of 4 mm is deposited on the back side of the N-type silicon wafer by means of LPCVD; and the N-type doped polysilicon layer with the thickness of 150 nm is formed by means of LPCVD and P diffusion; and the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate 1 with the a thickness of 75 nm is deposited by means of PECVD.

(61) At step C, each of the front-side silver main grids are designed in a first segmented structure, the first segmented structure includes a plurality of first grid segments, and the front-side silver main grids are distributed in aluminum fine grid lines; a number of the front-side aluminum fine grids is 112, with the width being 32 um and the height being 18 um; and each of the plurality of first grid segments of the front-side silver main grids has a length of 5 mm, a width of 1 mm and a height of 6 um, and a number of the front-side silver main grids is 8.

(62) At step D, a number of the back-side aluminum fine grids is 135, with the width being 100 um and the height being 18 um; the back-side silver main grids are designed in a second segmented structure, and the second segmented structure includes a plurality of second grid segments; and each of the plurality of second grid segments of the back-side silver main grid has a length of 5 mm, a width of 1 mm and a height of 5 um, and a number of the front-side silver main grids is 8.

(63) Comparative embodiment 3 (the difference between this comparative embodiment and Embodiment 1 lies in that UV laser ablation is only used on the front side of the cell to remove part of passivation dielectric film the SiN.sub.xH.sub.y layer.)

(64) An N-type TOPCon cell includes an N-type substrate 1. A P-type doped region layer 6, an AlO.sub.x layer 7 and a first SiN.sub.xH.sub.y layer 81 are successively provided, from inside to outside, on a front side of the N-type substrate 1; a tunnel oxide layer 9, an N-type doped polysilicon layer 10 and a second SiN.sub.xH.sub.y layer 82 are successively provided, from inside to outside, on a back side of the N-type substrate 1; and front-side silver main grids 2 and front-side aluminum fine grids 3 are provided on the first SiN.sub.xH.sub.y layer 81, and back-side silver main grids 4 and back-side aluminum fine grids 5 are provided on the second SiN.sub.xH.sub.y layer 82.

(65) A thickness of each the front-side silver main grids 2 is less than a thickness of each the front-side aluminum fine grids 3, and the front-side silver main grids 2 are distributed in the front-side aluminum fine grids 3; and a thickness of each of the back-side silver main grids 4 is less than a thickness of each of the back-side aluminum fine grids 5, and the back-side silver main grids 4 are distributed in the back-side aluminum fine grids 5. First contact grooves are provided on the AlO.sub.x layer 7 and the first SiN.sub.xH.sub.y layer 8 on the front side of the N-type substrate 1; and second contact grooves are provided on the second SiN.sub.xH.sub.y layer 8 on the back side of the N-type substrate 1. The front-side aluminum fine grids 3 pass through the first contact grooves to form first local contact points 111 with the AlO.sub.x layer 7. The back-side aluminum fine grids 5 pass through the second contact grooves to form second local contact points 112 with the N-type doped polysilicon layer 10.

(66) A method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes includes the following processes: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and N-type doped a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.P diffusion on the back side of the substrate.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on the front side of the substrate.fwdarw.deposition of a second SiN.sub.xH.sub.y preparatory layer on the back side of the substrate.fwdarw.UV laser ablation on the front side of the substrate and the back side of the substrate.fwdarw.screen printing. The preparation process specifically includes the following steps.

(67) At step A, namely the step of preparation of an N-type double-sided cell before metallization: an N-type monocrystalline silicon wafer is used as the substrate, the P-type doped region layer is formed on a front side of the N-type monocrystalline silicon wafer successively by means of B diffusion, a AlO.sub.x layer on the front side of the N-type substrate 1 with the thickness of 8 nm and first SiN.sub.xH.sub.y layer on the front side of the N-type substrate 1 with the thickness of 80 nm are deposited by means of PECVD, a tunnel oxide layer on the back side of the N-type substrate 1 with the thickness of 4 mm is deposited on the back side of the N-type silicon wafer by means of LPCVD; and the N-type doped polysilicon layer with the thickness of 150 nm is formed by means of LPCVD and P diffusion; and the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate 1 with the a thickness of 75 nm is deposited by means of PECVD.

(68) At step B, UV laser ablation is performed on a front surface of a preparatory cell prepared by a step A to remove part of passivation dielectric film of a SiN.sub.xH.sub.y layer; and UV laser ablation is performed on a back side of the cell to remove part of passivation dielectric film of the SiN.sub.xH.sub.y layer. A spot diameter of a UV laser is 20 um, and space between two adjacent of spots of the UV laser is 350 um; a front-side ablation film-removing depth is consistent with thickness of the SiN.sub.xH.sub.y layer; and a back-side ablation film-removing depth is consistent with a thickness of the passivation dielectric film of the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate 1.

(69) At step C, aluminum paste is used to print and sinter the front surface of the cell, so as to form a local contact point H-type front-side aluminum fine grids line electrode, where each of the front-side silver main grids are designed in a first segmented structure, the first segmented structure includes a plurality of first grid segments, and the front-side silver main grids are distributed in aluminum fine grid lines; a number of the front-side aluminum fine grids is 112, each of the front-side aluminum fine grids with the width being 32 um and the height being 18 um; and each first grid segments of the front-side silver main grid has a length of 5 mm, a width of 1 mm and a height of 6 um, and the number of the front-side silver main grids is 8.

(70) At step D, weak burn-through type aluminum paste is used to print and sinter the back side of the cell, so as to form a local contact point H-type back-side aluminum fine grids line electrode, where a number of the back-side aluminum fine grids is 135, with the width being 100 um and the height being 18 um; and the back-side silver main grids are designed in a second segmented structure, and the second segmented structure includes a plurality of second grid segments; each of the plurality of second grid segments has a length of 5 mm, a width of 1 mm and a height of 5 um, and a number of the back-side silver main grids is 8. The aluminum fine grid formed on the back side by means of sintering forms an ohmic contact with the N-type doped polysilicon layer, without forming a BSF layer.

(71) Comparative embodiment 4 (the difference between this comparative embodiment and Embodiment 1 lies in that, the UV laser is replaced with a green-light laser.)

(72) An N-type TOPCon cell includes an N-type substrate 1. A P-type doped region layer 6, an AlO.sub.x layer 7 and a first SiN.sub.xH.sub.y layer 81 are successively provided, from inside to outside, on a front side of the N-type substrate 1; a tunnel oxide layer 9, an N-type doped polysilicon layer 10 and a second SiN.sub.xH.sub.y layer 82 are successively provided, from inside to outside, on a back side of the N-type substrate 1; and front-side silver main grids 2 and front-side aluminum fine grids 3 are provided on the first SiN.sub.xH.sub.y layer 81, and back-side silver main grids 4 and back-side aluminum fine grids 5 are provided on the second SiN.sub.xH.sub.y layer 82.

(73) A thickness of each the front-side silver main grids 2 is less than a thickness of each the front-side aluminum fine grids 3, and the front-side silver main grids 2 are distributed in the front-side aluminum fine grids 3; and a thickness of each of the back-side silver main grids 4 is less than a thickness of each of the back-side aluminum fine grids 5, and the back-side silver main grids 4 are distributed in the back-side aluminum fine grids 5. First contact grooves are provided on the first AlO.sub.x layer 7 and the first SiN.sub.xH.sub.y layer 8 on the front side of the N-type substrate 1; and second contact grooves are provided on the second SiN.sub.xH.sub.y layer 8 on the back side of the N-type substrate 1. The front-side aluminum fine grids 3 pass through the first contact grooves to form first local contact points 111 with the AlO.sub.x layer 7. The back-side aluminum fine grids 5 pass through the second contact grooves to form second local contact points 112 with the N-type doped polysilicon layer 10.

(74) A method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes includes the following processes: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and N-type doped a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.P diffusion on the back side of the substrate.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on a front side of the substrate.fwdarw.deposition of a second SiN.sub.xH.sub.y preparatory layer on the back side of the substrate.fwdarw.green-light laser ablation on the front side of the substrate and the back side of the substrate.fwdarw.screen printing. The preparation process specifically includes the following steps.

(75) At step A, namely the step of preparation of an N-type double-sided cell before metallization: an N-type monocrystalline silicon wafer as the substrate, the P-type doped region layer is formed on a front side of the N-type monocrystalline silicon wafer successively by means of B diffusion, a AlO.sub.x preparatory layer on the front side of the N-type substrate 1 with the thickness of 8 nm and first SiN.sub.xH.sub.y preparatory layer on the front side of the N-type substrate 1 with the thickness of 80 nm are deposited by means of PECVD, a tunnel oxide layer on the back side of the N-type substrate 1 with the thickness of 4 mm is deposited on the back side of the N-type silicon wafer successively by means of LPCVD; the N-type doped polysilicon layer with the thickness of 150 nm is formed by means of LPCVD and P diffusion; and the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate 1 with the a thickness of 75 nm is deposited by means of PECVD.

(76) At step B, UV laser ablation is performed on a front surface of a preparatory the cell prepared by a step A to remove part of passivation dielectric film of the AlO.sub.x preparatory layer and an SiN.sub.xH.sub.y preparatory layer; and green-light laser ablation is performed on a back side of the cell prepared by the step A to remove part of passivation dielectric film of the second SiN.sub.xH.sub.y preparatory layer. A spot diameter of a green-light laser is 20 um, and a space s between two adjacent of spots of the green-light laser is 350 um; a front-side ablation film-removing depth is consistent with thicknesses of the AlO.sub.x layer and the first SiN.sub.xH.sub.y layer; and a back-side ablation film-removing depth is consistent with a thickness of the passivation dielectric film of the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate 1.

(77) At step C, aluminum paste is used to print and sinter the front surface of the cell by the step B, so as to form a local contact point H-type front-side aluminum fine grids line electrode, where each of the front-side silver main grids are designed in a first segmented structure, the first segmented structure includes a plurality of first grid segments, and each of a front-side silver main grids is distributed in aluminum fine grid lines; the number of the front-side aluminum fine grids is 112, each of the front-side aluminum fine grids with the width being 32 um and each of the front-side aluminum fine grids with the height being 18 um; and each of the plurality of first grid segments of the front-side silver main grids has a length of 5 mm, a width of 1 mm and a height of 6 um, and a number of the front-side silver main grids is 8.

(78) At step D, weak burn-through type aluminum paste is used to print and sinter a back side of the cell by the step B or step C, so as to form a local contact point H-type back-side aluminum fine grids line electrode, where a number of the back-side aluminum fine grids is 135, each of the back-side aluminum fine grids with the width being 100 um and each of the back-side aluminum fine grids the height being 18 um; and a back-side silver main grids are designed in a second segmented structure, and the second segmented structure includes a plurality of second grid segments; each of the plurality of second grid segments has a length of 5 mm, a width of 1 mm and a height of 5 um, and a number of the back-side silver main grids is 8. The aluminum fine grid formed on the back side by means of sintering forms an ohmic contact with the N-type doped polysilicon layer, without forming a BSF layer.

(79) Comparative embodiment 5 (the difference between this comparative embodiment and Embodiment 1 lies in that, the number of the front-side aluminum fine grids is too few, which is only 60.)

(80) An N-type TOPCon cell includes an N-type substrate 1. A P-type doped region layer 6, an AlO.sub.x layer 7 and a first SiN.sub.xH.sub.y layer 81 are successively provided, from inside to outside, on a front side of the N-type substrate 1; a tunnel oxide layer 9, an N-type doped polysilicon layer 10 and a second SiN.sub.xH.sub.y layer 82 are successively provided, from inside to outside, on a back side of the N-type substrate 1; and front-side silver main grids 2 and front-side aluminum fine grids 3 are provided on the first SiN.sub.xH.sub.y layer 81, and back-side silver main grids 4 and back-side aluminum fine grids 5 are provided on the second SiN.sub.xH.sub.y layer 82.

(81) A thickness of each the front-side silver main grids 2 is less than a thickness of each the front-side aluminum fine grids 3, and the front-side silver main grids 2 are distributed in the front-side aluminum fine grids 3; and a thickness of each the back-side silver main grids 4 is less than a thickness of each the back-side aluminum fine grids 5, and the back-side silver main grids 4 are distributed in the back-side aluminum fine grids 5. First contact grooves are provided on the AlO.sub.x layer 7 and the first SiN.sub.xH.sub.y layer 81 on the front side of the N-type substrate 1; and second contact grooves are provided on the second SiN.sub.xH.sub.y layer 82. The front-side aluminum fine grids 3 pass through the first contact grooves to form first local contact points 111 with the AlO.sub.x layer 7. The back-side aluminum fine grids 5 pass through the second contact grooves to form second local contact points 112 with the N-type doped polysilicon layer 10.

(82) A process for preparing the N-type TOPCon cell includes: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and N-type doped a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.P diffusion on the back side of the substrate.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on the front side of the substrate.fwdarw.deposition of a second SiN.sub.xH.sub.y preparatory layer on the back side of the substrate.fwdarw.UV laser ablation on the front side of the substrate and the back side of the substrate.fwdarw.screen printing. The preparation process specifically includes the following steps.

(83) At step A, namely the step of preparation of an N-type double-sided cell before metallization: an N-type monocrystalline silicon wafer as the substrate, the P-type doped region layer is formed on a front side of the N-type monocrystalline silicon wafer successively by means of B diffusion, a AlO.sub.x preparatory layer on the front side of the N-type substrate 1 with the thickness of 8 nm and the first SiN.sub.xH.sub.y preparatory layer with the thickness of 80 nm are deposited by means of PECVD, a tunnel oxide layer on the back side of the N-type substrate 1 with the thickness of 4 mm is deposited on the back side of the N-type silicon wafer by means of LPCVD; and the N-type doped polysilicon layer with the thickness of 150 nm is formed by means of LPCVD and P diffusion; and the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate 1 with the a thickness of 75 nm is deposited by means of PECVD.

(84) At step B, UV laser ablation is performed on a front surface of a preparatory the cell prepared by a step A to remove part of passivation dielectric film of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer; and UV laser ablation is performed on a back side of the cell prepared by the step A to remove part of passivation dielectric film of the second SiN.sub.xH.sub.y preparatory layer. A spot diameter of a UV laser is 20 um, and a space between two adjacent of spots of the UV laser is 350 um; a front-side ablation film-removing depth is consistent with thicknesses of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer; and a back-side ablation film-removing depth is consistent with a thickness of the passivation dielectric film of the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate 1.

(85) At step C, aluminum paste is used to print and sinter the front surface of the cell by the step B, so as to form a local contact point H-type front-side aluminum fine grids line electrode, where each of the front-side silver main grids are designed in a first segmented structure, the first segmented structure includes a plurality of first grid segments, and the front-side silver main grids are distributed in aluminum fine grid lines; a number of the front-side aluminum fine grids is 60, with the width being 32 um and the height being 18 um; and each of the plurality of first grid segments of the front-side silver main grid has a length of 5 mm, a width of 1 mm and a height of 6 um, and a number of the front-side silver main grids is 8.

(86) At step D, weak burn-through type aluminum paste is used to print and sinter a back side of the cell by the step B or step C, so as to form a local contact point H-type back-side aluminum fine grids line electrode, where a number of the back-side aluminum fine grids is 135, each of the back-side aluminum fine grids with the width being 100 um and the height being 18 um; and each of the back-side silver main grids are designed in a second segmented structure, and the second segmented structure includes a plurality of second grid segments; each of the plurality of second grid segments has a length of 5 mm, a width of 1 mm and a height of 5 um, and a number of the back-side silver main grids is 8. The aluminum fine grid formed on the back side by means of sintering forms an ohmic contact with the N-type doped polysilicon layer, without forming a BSF layer.

(87) Comparative embodiment 6 (the difference between this comparative embodiment and Embodiment 1 lies in that, the number of the front-side aluminum fine grids is too many, which is 140.)

(88) An N-type TOPCon cell includes an N-type substrate 1. A P-type doped region layer 6, an AlO.sub.x layer 7 and a first SiN.sub.xH.sub.y layer 81 are successively provided, from inside to outside, on a front side of the N-type substrate 1; a tunnel oxide layer 9, an N-type doped polysilicon layer 10 and a second SiN.sub.xH.sub.y layer 82 are successively provided, from inside to outside, on a back side of the N-type substrate 1; and front-side silver main grids 2 and front-side aluminum fine grids 3 are provided on the first SiN.sub.xH.sub.y layer 81, and back-side silver main grids 4 and back-side aluminum fine grids 5 are provided on the second SiN.sub.xH.sub.y layer 82.

(89) A thickness of each of the front-side silver main grids 2 is less than a thickness of each of the front-side aluminum fine grids 3, and the front-side silver main grids 2 are distributed in the front-side aluminum fine grids 3; and a thickness of each of the back-side silver main grids 4 is less than a thickness of each the back-side aluminum fine grids 5, and the back-side silver main grids 4 are distributed in the back-side aluminum fine grids 5. First contact grooves are provided on the AlO.sub.x layer 7 and the first SiN.sub.xH.sub.y layer 8 on the front side of the N-type substrate 1; and second contact grooves are provided on the second SiN.sub.xH.sub.y layer 8 on the back side of the N-type substrate 1. The front-side aluminum fine grids 3 pass through the first contact grooves to form first local contact points 111 with the AlO.sub.x layer 7. The back-side aluminum fine grids 5 pass through the second contact grooves to form second local contact points 112 with the N-type doped polysilicon layer 10.

(90) A method for preparing the N-type TOPCon cell with double-sided aluminum paste electrodes includes the following processes: texturing.fwdarw.B diffusion.fwdarw.BSG removal.fwdarw.alkali polishing.fwdarw.depositing a tunnel oxide layer and N-type doped a polysilicon layer on a back side of a substrate by means of LPCVD.fwdarw.P diffusion on the back side of the substrate.fwdarw.PSG removal.fwdarw.plating removal.fwdarw.deposition of an AlO.sub.x preparatory layer and a first SiN.sub.xH.sub.y preparatory layer on a front side of the substrate.fwdarw.deposition of a second SiN.sub.xH.sub.y preparatory layer on the back side of the substrate.fwdarw.UV laser ablation on the front side of the substrate and the back side of the substrate.fwdarw.screen printing. The method includes the following specific preparation steps.

(91) At step A, namely the step of preparation of an N-type double-sided cell before metallization: an N-type monocrystalline silicon wafer is used as the substrate, the P-type doped region layer is formed on a front side of the N-type monocrystalline silicon wafer successively by means of B diffusion, a AlO.sub.x preparatory layer on the front side of the N-type substrate 1 with the thickness of 8 nm and the first SiN.sub.xH.sub.y preparatory layer with the thickness of 80 nm are deposited by means of PECVD, a tunnel oxide layer on the back side of the N-type substrate 1 with the thickness of 4 mm is deposited on the back side of the N-type silicon wafer by means of LPCVD; and the N-type doped polysilicon layer with the thickness of 150 nm is formed by means of LPCVD and P diffusion; and the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate 1 with the a thickness of 75 nm is deposited by means of PECVD.

(92) At step B, UV laser ablation is performed on a front surface of a preparatory cell prepared by a step A to remove part of passivation dielectric film of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer; and UV laser ablation is performed on a back side of the cell prepared by the step A to remove part of passivation dielectric film of the second SiN.sub.xH.sub.y preparatory layer. A spot diameter of a UV laser is 20 um, and a space between two adjacent of spots of the UV laser is 350 um; a front-side ablation film-removing depth is consistent with thicknesses of the AlO.sub.x preparatory layer and the first SiN.sub.xH.sub.y preparatory layer; and a back-side ablation film-removing depth is consistent with a thickness of the passivation dielectric film of the second SiN.sub.xH.sub.y layer on the back side of the N-type substrate 1.

(93) At step C, aluminum paste is used to print and sinter the front surface of the cell by the step B, so as to form a local contact point H-type front-side aluminum fine grid line electrode, where the front-side silver main grids are designed in a first segmented structure, the first segmented structure includes a plurality of first grid segments, and each of a front-side silver main grids is distributed in aluminum fine grid lines; a number of the front-side aluminum fine grids is 140, each of the front-side aluminum fine grids with the width being 32 um and the height being 18 um; and each of the plurality of first grid segments of the front-side silver main grid has a length of 5 mm, a width of 1 mm and a height of 6 um, and a number of the front-side silver main grids is 8.

(94) At step D, weak burn-through type aluminum paste is used to print and sinter the back side of the cell by the step B or step C, so as to form a local contact point H-type back-side aluminum fine grid line electrode, where a number of the back-side aluminum fine grids is 135, with each of the back-side aluminum fine grids has a width being 100 um and the height being 18 um; and each of the back-side silver main grids are designed in a second segmented structure, and the second segmented structure includes a plurality of second grid segments; each of the plurality of second grid segments has a length of 5 mm, a width of 1 mm and a height of 5 um, and a number of the back-side silver main grids is 8. The aluminum fine grid formed on the back side by means of sintering forms an ohmic contact with the N-type doped polysilicon layer, without forming a BSF layer.

(95) TABLE-US-00001 TABLE 1 Performance parameters of a cell in embodiments and comparative embodiments Performance Relative Relative Relative Relative value of value of value of value of battery open-circuit current fill Item efficiency voltage density factor Embodiment 1 23.61 705 40.55 82.60 Embodiment 2 23.23 720 41.22 78.30 Embodiment 3 23.54 696 40.50 83.54 Embodiment 4 23.42 702 40.40 82.60 Embodiment 5 23.37 700 40.45 82.55 Comparative 23.45 695 40.85 82.60 embodiment 1 Comparative 23.29 698 40.30 82.80 embodiment 2 Comparative 23.42 701 40.40 82.70 embodiment 3 Comparative 23.13 692 40.35 82.85 embodiment 4 Comparative 23.04 710 41.50 78.20 embodiment 5 Comparative 23.26 690 40.10 84.10 embodiment 6

(96) Conclusion analysis: it can be seen, by synthesizing results in Embodiments 1-5, that a cell can only have higher cell efficiency and current density, and higher sunlight conversion efficiency by using an N-type TOPCon cell structure prepared by the method for preparing the N-type TOPCon cell of the present invention, such that a loss rate of sunlight is greatly reduced, and a manufacturing cost of the cell is greatly saved.

(97) The difference between Comparative embodiment 1 and Embodiment 1 lies in that, front-side silver main grids are provided on a front side of the N-type substrate 1, and there is not front-side aluminum fine grids on the front side of the N-type substrate 1; back-side silver main grids are provided on a back side of the N-type substrate 1, and there is not back-side aluminum fine grids on the back side of the N-type substrate 1. A silver grids have a low light-shading ratio, such that the current density is increased; however, metal compounding is increased at the same time in Comparative embodiment 1, and an open-circuit voltage is obviously reduced, such that corresponding performance of the N-type TOPCon cell is decreased relative to Embodiment 1.

(98) The difference between Comparative embodiment 2 and Embodiment 1 lies in that, the UV laser is not used on a front side of the N-type substrate 1 and a back side of the N-type substrate 1 for film opening. The aluminum paste needs to be corroded by means of a vitreous body of its own, resulting in excessive damage to the passivation film, and both the open-circuit voltage and the current density are reduced, such that the corresponding performance of the N-type TOPCon cell is decreased relative to Embodiment 1.

(99) The difference between Comparative embodiment 3 and Embodiment 1 lies in that, the UV laser is only used on a front side of the N-type substrate 1 for film opening. The aluminum paste on a back side of the N-type substrate 1 needs to be corroded by means of a vitreous body of its own, resulting in excessive damage of a passivation dielectric film of the back-side of the N-type substrate 1, and both a open-circuit voltage and a current density are reduced, such that the corresponding performance of the N-type TOPCon cell is decreased relative to Embodiment 1.

(100) The difference between Comparative embodiment 4 and Embodiment 1 lies in that, the UV laser is replaced with the green-light laser. The green-light laser has stronger penetration power and generates a larger heat-affected zone to a film layer during ablation, the film layer is part of passivation dielectric film of the AlO.sub.x preparatory layer, the first SiN.sub.xH.sub.y preparatory layer and the second SiN.sub.xH.sub.y preparatory layer; and both the open-circuit voltage and the current density are obviously reduced, such that the corresponding performance of the N-type TOPCon cell is decreased relative to Embodiment 1.

(101) The difference between Comparative embodiment 5 and Embodiment 1 lies in that, a number of a front-side aluminum grids is too few, which is only 60, and the fill factor is obviously reduced, such that the corresponding performance of the N-type TOPCon cell is decreased relative to Embodiment 1.

(102) The difference between Comparative embodiment 6 and Embodiment 1 lies in that, a number of the front-side aluminum grids is too many, which is 140; both the open-circuit voltage and the current density are obviously reduced; and although the fill factor is obviously increased, the corresponding performance of the N-type TOPCon cell is eventually decreased relative to Embodiment 1.

(103) It can be learned, from Embodiments 1-5 and Comparative embodiments 1-6, that only a solution within the scope of the claims of the present disclosure can meet the above requirements in all respects, resulting in an optimized solution and an N-type TOPCon cell with double-sided aluminum paste electrodes with optimal performance. However, replacement/addition or subtraction of each deposition layer, or changes in preparation sequence, will have a corresponding negative impact.

(104) The raw materials and devices used in the present disclosure, if not specifically stated, are common raw materials and devices in the art; and the methods used in the present invention, if not specifically stated, are conventional methods in the art.

(105) The above are only preferred embodiments of the present invention, not any limitation to the present invention. Any simple modification, change and equivalent transformation of the above embodiments according to the technical substance of the present disclosure all still fall within the scope of protection of the technical solution of the present invention.