Solar cell and photovoltaic module

1 . A solar cell, comprising:

a silicon substrate, having a front surface and a rear surface opposite to the front surface, wherein the silicon substrate includes at least one of a phosphorus (P) element, a bismuth (Bi) element, an antimony (Sb) element, or an arsenic (As) element;

a passivation layer including an aluminum oxide (Al x O y ) material formed over the front surface, wherein ⅓≤x/y≤3, x/y representing a ratio of content of aluminum to content of oxygen in the passivation layer;

a first antireflection layer including a silicon nitride “(Si i N j )” material formed over the passivation layer, wherein 0.5≤i/j≤10, i/j representing a ratio of content of silicon to content of nitrogen in the first antireflection layer;

a second antireflection layer including a silicon oxynitride (Si c N d O e ) material formed over the first antireflection layer, wherein 0.5≤c/d≤10, and 0.25≤d/e≤2, c/d representing a ratio of content of silicon to content of nitrogen in the second antireflection layer, and d/e representing a ratio of content of nitrogen to content of oxygen in the second antireflection layer;

a third antireflection layer including a silicon oxide (Si a O b ) material formed over the second antireflection layer, wherein 0.5≤a/b≤3, a/b representing a ratio of content of silicon to content of oxygen in the third antireflection layer;

a tunneling dielectric layer formed over the rear surface; and

a doped conductive layer formed over the tunneling dielectric layer;

wherein in a direction away from the first antireflection layer, content percentage of silicon in the second antireflection layer gradually decreases, content percentage of nitrogen in the second antireflection layer gradually decreases, and content percentage of oxygen in the second antireflection layer gradually increases;

wherein the second antireflection layer includes a plurality second sub-antireflection layers stacked in the direction away from the first antireflection layer, each of the plurality of second sub-antireflection layers includes a silicon oxynitride material; and

wherein in the direction away from the first antireflection layer, content percentage of silicon in the plurality of second sub-antireflection layers decreases layer by layer, content percentage of nitrogen in the plurality of second sub-antireflection layers decreases layer by layer, and content percentage of oxygen in the plurality of second sub-antireflection layers increases layer by layer.

2 . The solar cell according to claim 1 , wherein the third antireflection layer has an uneven surface facing away from the second antireflection layer.

3 . The solar cell according to claim 1 , wherein the third antireflection layer has a minimum thickness and a maximum thickness, and a ratio of the minimum thickness to the maximum thickness is not greater than 0.5.

4 . The solar cell according to claim 1 , wherein in a direction away from the second antireflection layer, content percentage of silicon in the third antireflection layer gradually decreases, and content percentage of oxygen in the third antireflection layer gradually increases.

5 . The solar cell according to claim 4 , wherein the third antireflection layer includes N third sub-antireflection layers stacked in the direction away from the second antireflection layer, each of the N third sub-antireflection layers includes a silicon oxide material, wherein N is a positive integer greater than or equal to 2; and

in the direction away from the second antireflection layer, content percentage of silicon in the N third sub-antireflection layers decreases layer by layer, and content percentage of oxygen in the N third sub-antireflection layers increases layer by layer.

6 . The solar cell according to claim 5 , wherein in the direction away from the second antireflection layer, a single third sub-antireflection layer is 2 nm to 15 nm in thickness, and the third antireflection layer is 2 nm to 40 nm in thickness.

7 . The solar cell according to claim 5 , wherein a single third sub-antireflection layer has uniformly-distributed silicon content and uniformly-distributed oxygen content.

8 . The solar cell according to claim 1 , wherein the third antireflection layer is 2 nm to 40 nm in thickness.

9 . The solar cell according to claim 8 , wherein the tunneling dielectric layer is 1 nm to 2.5 nm in thickness, and the third antireflection layer is thicker than the tunneling dielectric layer.

10 . The solar cell according to claim 1 , wherein the third antireflection layer further includes nitrogen, and content percentage of nitrogen in the third antireflection layer is less than 5%.

11 . The solar cell according to claim 1 , wherein in a direction away from the passivation layer, content percentage of silicon in the first antireflection layer gradually decreases, and content percentage of nitrogen in the first antireflection layer gradually increases.

12 . The solar cell according to claim 11 , wherein the first antireflection layer includes M first sub-antireflection layers stacked in the direction away from the passivation layer, each of the M first sub-antireflection layers includes a silicon nitride material, wherein M is a positive integer greater than or equal to 2; and

in the direction away from the passivation layer, content percentage of silicon in the M first sub-antireflection layers decreases layer by layer, and content percentage of nitrogen in the M first sub-antireflection layers increases layer by layer.

13 . The solar cell according to claim 12 , wherein thicknesses of the M first sub-antireflection layers increase layer by layer in the direction away from the passivation layer, one of the M first sub-antireflection layers closest to the passivation layer is 2 nm to 15 nm in thickness, and the first antireflection layer is 5 nm to 50 nm in thickness.

14 . The solar cell according to claim 12 , wherein a single first sub-antireflection layer has uniformly-distributed silicon content and uniformly-distributed nitrogen content.

15 . The solar cell according to claim 1 , wherein the first antireflection layer further includes oxygen, and content percentage of oxygen in the first antireflection layer is less than 5%.

16 . The solar cell according to claim 1 , wherein in the direction away from the first antireflection layer, a single second sub-antireflection layer is 5 nm to 40 nm in thickness, and the second antireflection layer is 10 nm to 60 nm in thickness.

17 . The solar cell according to claim 1 , wherein the second antireflection layer is 10 nm to 60 nm in thickness.

18 . A photovoltaic module, comprising:

a plurality of cell strings, each formed by connecting a plurality of solar cells;

an encapsulation film, configured to cover surfaces of the plurality of cell strings; and

a cover plate, configured to cover a surface of the encapsulation film facing away from the plurality of cell strings;

wherein each of the plurality of solar cells comprises:

a silicon substrate, having a front surface and a rear surface opposite to the front surface, wherein the silicon substrate includes at least one of a phosphorus (P) element, a bismuth (Bi) element, an antimony (Sb) element, or an arsenic (As) element;

a passivation layer including an aluminum oxide (Al x O y ) material formed over the front surface, wherein ⅓≤x/y≤3, x/y representing a ratio of content of aluminum to content of oxygen in the passivation layer;

a first antireflection layer including a silicon nitride “(Si i N j )” material formed over the passivation layer, wherein 0.5≤i/j≤10, i/j representing a ratio of content of silicon to content of nitrogen in the first antireflection layer;

a second antireflection layer including a silicon oxynitride (Si c N d O e ) material formed over the first antireflection layer, wherein 0.5≤c/d≤10, and 0.25≤d/e≤2, c/d representing a ratio of content of silicon to content of nitrogen in the second antireflection layer, and d/e representing a ratio of content of nitrogen to content of oxygen in the second antireflection layer;

a third antireflection layer including a silicon oxide (Si a O b ) material formed over the second antireflection layer, wherein 0.5≤a/b≤3, a/b representing a ratio of content of silicon to content of oxygen in the third antireflection layer;

a tunneling dielectric layer formed over the rear surface; and

a doped conductive layer formed over the tunneling dielectric layer;

wherein in a direction away from the first antireflection layer, content percentage of silicon in the second antireflection layer gradually decreases, content percentage of nitrogen in the second antireflection layer gradually decreases, and content percentage of oxygen in the second antireflection layer gradually increases;

wherein the second antireflection layer includes a plurality second sub-antireflection layers stacked in the direction away from the first antireflection layer, each of the plurality of second sub-antireflection layers includes a silicon oxynitride material; and

wherein in the direction away from the first antireflection layer, content percentage of silicon in the plurality of second sub-antireflection layers decreases layer by layer, content percentage of nitrogen in the plurality of second sub-antireflection layers decreases layer by layer, and content percentage of oxygen in the plurality of second sub-antireflection layers increases layer by layer.