Method for preparing solar cell
Provided are a method for preparing a solar cell, a solar cell, and a photovoltaic module. The method for preparing a solar cell includes: performing double-sided texturing on a silicon substrate; performing boron diffusion on the silicon substrate to form a boron diffusion layer and a borosilicate glass layer on both a front side and a back side of the silicon substrate; the front side of the silicon substrate having a first region and a second region, and removing the borosilicate glass layer and the boron diffusion layer in the second region by using laser, wherein wet oxygen and dry oxygen are introduced during the boron diffusion on the silicon substrate with a ratio ω of the wet oxygen to the dry oxygen satisfying 0%<ω≤20%; a density ρ 1 of the borosilicate glass layer satisfies 1.32 g/cm 3 <ρ1 ≤2.65 g/cm 3 .
1 . A method for preparing a solar cell, comprising:
performing double-sided texturing on a silicon substrate;
performing boron diffusion on the silicon substrate to form a boron diffusion layer and a borosilicate glass layer on both a front side and a back side of the silicon substrate;
the front side of the silicon substrate having a first contact region and a first non-contact region, and removing the borosilicate glass layer and the boron diffusion layer in the first non-contact region by using laser;
wherein wet oxygen and dry oxygen are introduced during the boron diffusion on the silicon substrate with a ratio ω of the wet oxygen to the dry oxygen satisfying 0%<ω≤20%; a density ρ 1 of the borosilicate glass layer satisfies 1.32 g/cm 3 <ρ 1 ≤2.65 g/cm 3 .
2 . The method of claim 1 , wherein in the step of removing the borosilicate glass layer and the boron diffusion layer in the first non-contract region by using laser, an energy density γ 1 required for the laser to remove the borosilicate glass layer and the boron diffusion layer is inversely proportional to the ratio ω of the wet oxygen to the dry oxygen.
3 . The method of claim 2 , wherein a ratio of the energy density γ 1 required for the laser to remove the borosilicate glass layer and the boron diffusion layer to a rated energy density γ of the laser satisfies 0.5≤γ 1 /γ<1.
4 . The method of claim 1 , wherein when the wet oxygen and the dry oxygen are introduced during the boron diffusion on the silicon substrate with a ratio ω of the wet oxygen to the dry oxygen satisfying 0% to 20%, a flow rate of the wet oxygen is in a range from 1000 sccm to 2000 sccm, and a flow rate of the dry oxygen is in a range from 2000 sccm to 20000 sccm.
5 . The method of claim 3 , wherein in the step of removing the borosilicate glass layer and the boron diffusion layer in the first non-contact region by using laser, the laser is a red nanosecond laser.
6 . The method of claim 5 , wherein the laser has a nanosecond pulse width of 20 ns to 200 ns, a scanning speed of 8000 mm/s to 50000 mm/s, and a power of 30 W to 50 W.
7 . The method of claim 3 , wherein in the step of removing the borosilicate glass layer and the boron diffusion layer in the first non-contact region by using laser, the laser is a green nanosecond laser.
8 . The method of claim 7 , wherein the laser has a nanosecond pulse width of 20 ns to 200 ns, a scanning speed of 8000 mm/s to 50000 mm/s, and a power of 30 W to 50 W.
9 . The method of claim 1 , wherein in the step of performing the boron diffusion on the silicon substrate to form the boron diffusion layer and the borosilicate glass layer on both the front side and the back side of the silicon substrate, a thickness D 1 of the borosilicate glass layer satisfies 40 nm to 80 nm.
10 . The method of claim 9 , wherein in the step of performing the boron diffusion on the silicon substrate to form the boron diffusion layer and the borosilicate glass layer on both the front side and the back side of the silicon substrate, the oxygen is introduced at a flow rate of 2000 sccm to 20000 sccm, a temperature is in a range from 850° C. to 1000° C., a tube furnace pressure is in a range from 740 mBar to 760 mBar.
11 . The method of claim 1 , wherein after the step of the front side of the silicon substrate having the first contact region and the first non-contact region and removing the borosilicate glass layer and the boron diffusion layer in the first non-contact region by using laser, the method further comprising:
removing the boron diffusion layer and the borosilicate glass layer on the back side of the silicon substrate;
sequentially forming a tunnelling oxide layer, a phosphorus diffusion layer, and a phosphosilicate glass layer on the front side and the back side of the silicon substrate;
the back side of the silicon substrate having a second contact region and a second non-contact region, removing the tunnelling oxide layer, the phosphorus diffusion layer, and the phosphosilicate glass layer in the second non-contact region;
removing the phosphosilicate glass layer on the front side of the silicon substrate;
performing secondary texturing on the silicon substrate;
depositing a passivation layer on the front side and the back side of the silicon substrate; and
preparing electrodes in the first contact region and the second contact region.
12 . The method of claim 11 , wherein the step of performing secondary texturing on the silicon substrate comprises:
removing the phosphorus diffusion layer and the tunnelling oxide layer on the front side of the silicon substrate, and the phosphosilicate glass layer on the back side of the silicon substrate, and
texturing a surface of the silicon substrate corresponding to the first non-contact region and the second non-contact region to form a textured surface.
13 . The method of claim 3 , wherein after the step of the front side of the silicon substrate having the first contact region and the first non-contact region and removing the borosilicate glass layer and the boron diffusion layer in the first non-contact region by using laser, the method further comprising:
removing the boron diffusion layer and the borosilicate glass layer on the back side of the silicon substrate;
sequentially forming a tunnelling oxide layer, a phosphorus diffusion layer, and a phosphosilicate glass layer on the front side and the back side of the silicon substrate;
the back side of the silicon substrate having a second contact region and a second non-contact region, removing the tunnelling oxide layer, the phosphorus diffusion layer, and the phosphosilicate glass layer in the second non-contact region;
removing the phosphosilicate glass layer on the front side of the silicon substrate;
performing secondary texturing on the silicon substrate;
depositing a passivation layer on the front side and the back side of the silicon substrate; and
preparing electrodes in the first contact region and the second contact region.
14 . The method of claim 13 , wherein the step of performing secondary texturing on the silicon substrate comprises:
removing the phosphorus diffusion layer and the tunnelling oxide layer on the front side of the silicon substrate, and the phosphosilicate glass layer on the back side of the silicon substrate, and
texturing a surface of the silicon substrate corresponding to the first non-contact region and the second non-contact region to form a textured surface.
15 . The method of claim 1 , wherein the step of performing the boron diffusion on the silicon substrate to form the boron diffusion layer and the borosilicate glass layer on both the front side and the back side of the silicon substrate further comprises temperature raising, temperature holding, oxidation, and cooling.
16 . The method of claim 15 , wherein in steps of the temperature raising, temperature holding, oxidation, and cooling, the oxygen is introduced at a flow rate of 2000 sccm to 20000 sccm, the temperature is in a range from 850° C. to 1000° C., and the tube furnace pressure is in a range from 740 mBar to 760 mBar.
17 . The method of claim 11 , wherein a surface of the silicon substrate corresponding to the second contact region is a polished surface.
18 . The method of claim 11 , wherein a surface of the silicon substrate corresponding to the first contact region, the first non-contact region, and the second non-contact region is a textured surface.
19 . The method of claim 1 , wherein a ratio of energy density γ 1 required for the laser to remove the borosilicate glass layer and the boron diffusion layer to a rated energy density γ of the laser satisfies γ 1 /γ=0.5.
20 . The method of claim 11 , wherein the tunnelling oxide layer and the phosphorus diffusion layer that are located in the second contact region forms a passivation contact structure.