Heterojunction solar cell and preperation method thereof
A heterojunction solar cell and a preparation method therefor. The heterojunction solar cell comprises: a semiconductor substrate layer; and a back composite transparent conductive film located on one side of the semiconductor substrate layer. The back surface composite transparent conductive film comprises: a first back surface transparent conductive film; and a second back transparent conductive film located on the side surface of the first back transparent conductive film facing away from the semiconductor substrate layer. Both the first back transparent conductive film and the second back transparent conductive film are doped with group III heavy atoms, and the concentration of the group III heavy atoms in the second back transparent conductive film is less than that of the group III heavy atoms in the first back transparent conductive film.
1 . A heterojunction solar cell, comprising:
a semiconductor substrate layer; and
a back composite transparent conductive film located on one side of the semiconductor substrate layer,
wherein the back composite transparent conductive film comprises:
a first back transparent conductive film, and
a second back transparent conductive film located on a surface of a side of the first back transparent conductive film facing away from the semiconductor substrate layer,
wherein both the first back transparent conductive film and the second back transparent conductive film are doped with group III heavy atoms and a concentration of group III heavy atoms in the second back transparent conductive film is lower than that of the group III heavy atoms in the first back transparent conductive film,
wherein the back composite transparent conductive film further comprises a third back transparent conductive film located between the first back transparent conductive film and the semiconductor substrate layer and a work function of the third back transparent conductive film is higher than that of the first back transparent conductive film and higher than that of the second back transparent conductive film,
wherein mobility of the third back transparent conductive film is greater than that of the first back transparent conductive film and greater than that of the second back transparent conductive film, and
wherein a concentration of doping ions in the third back transparent conductive film is lower than the concentration of group III heavy atoms in the first back transparent conductive film and lower than the concentration of group III heavy atoms in the second back transparent conductive film.
2 . The heterojunction solar cell of claim 1 , wherein the group III heavy atoms comprise gallium atoms, material of the first back transparent conductive film comprises gallium-doped zinc oxide, and material of the second back transparent conductive film comprises gallium-doped zinc oxide.
3 . The heterojunction solar cell of claim 2 , wherein a ratio of a mass percentage concentration of gallium in the second back transparent conductive film to a mass percentage concentration of gallium in the first back transparent conductive film is in a range from 1:2 to 1:4.
4 . The heterojunction solar cell of claim 2 , wherein mass percentage concentration of gallium in the first back transparent conductive film is in a range from 1.5% to 2% and mass percentage concentration of gallium in the second back transparent conductive film is in a range from 0.5%-1%.
5 . The heterojunction solar cell of claim 2 , wherein a ratio of a thickness of the second back transparent conductive film to a thickness of the first back transparent conductive film is in a range from 1:4 to 1:3.
6 . The heterojunction solar cell of claim 2 , wherein thickness of the second back transparent conductive film ranges from 10 nm to 20 nm and thickness of the first back transparent conductive film ranges from 50 nm to 60 nm.
7 . The heterojunction solar cell of claim 1 , wherein
material of the third back transparent conductive film comprises tungsten-doped indium oxide.
8 . The heterojunction solar cell of claim 7 , wherein a mass percentage concentration of tungsten in the tungsten-doped indium oxide is in a range from 0.1% to 0.3%.
9 . The heterojunction solar cell of claim 7 , wherein a ratio of a thickness of the third back transparent conductive film to a thickness of the first back transparent conductive film is in a range from 1:5 to 1:6.
10 . The heterojunction solar cell of claim 1 , wherein:
the heterojunction solar cell further comprises a back grid line located on a side of the back composite transparent conductive film facing away from the semiconductor substrate layer,
the back grid line comprises a first sub-back grid line and a second sub-back grid line located on a surface of a side of the first sub-back grid line that faces away from the semiconductor substrate layer,
a conductivity of the first sub-back grid line is greater than a conductivity of the second sub-back grid line, and
a melting point of the second sub-back grid line is lower than that of the first sub-back grid line.
11 . The heterojunction solar cell of claim 10 , wherein material of the first sub-back grid line comprises copper and material of the second sub-back grid line comprises tin.
12 . The heterojunction solar cell of claim 10 , wherein a relationship between a thickness of the first sub-back grid line and a thickness of the second sub-back grid line is in a range from 5:1 to 9:1.
13 . The heterojunction solar cell of claim 10 , wherein an aspect ratio of the back grid line ranges from 0.8:2 to 1:2, a width of the back grid line ranges from 9 μm to 11 μm, and a height of the back grid line ranges from 4 μm to 6 μm.
14 . The heterojunction solar cell of claim 1 , wherein the heterojunction solar cell further comprises a front composite transparent conductive film located on a side of the semiconductor substrate layer facing away from the back composite transparent conductive film and wherein material of the front composite transparent conductive film comprises tungsten-doped indium oxide.
15 . A method for preparing a heterojunction solar cell, wherein the method comprises:
providing a semiconductor substrate layer; and
forming a back composite transparent conductive film on one side of the semiconductor substrate layer, wherein a process for forming the back composite transparent conductive film comprises:
forming a first back transparent conductive film on one side of the semiconductor substrate layer, and
forming a second back transparent conductive film on a surface of the side of the first back transparent conductive film facing away from the semiconductor substrate layer,
wherein both the first back transparent conductive film and the second back transparent conductive film are doped with group III heavy atoms and a concentration of group III heavy atoms in the second back transparent conductive film is lower than that of the group III heavy atoms in the first back transparent conductive film,
wherein the process for forming the back composite transparent conductive film further comprises forming a third back transparent conductive film on one side of the semiconductor substrate layer before forming a first back composite transparent conductive film,
wherein the third back transparent conductive film is located between the first back transparent conductive film and the semiconductor substrate layer after forming the first back transparent conductive film,
wherein a work function of the third back transparent conductive film is higher than that of the first back transparent conductive film and higher than that of the second back transparent conductive film,
wherein a mobility of the third back transparent conductive film is greater than that of the first back transparent conductive film and greater than that of the second back transparent conductive film, and
wherein a concentration of doping ions in the third back transparent conductive film is lower than that of group III heavy atoms in the first back transparent conductive film and lower than that of group III heavy atoms in the second back transparent conductive film.
16 . The method for preparing a heterojunction solar cell of claim 15 , wherein the method for preparing a heterojunction solar cell further comprises forming a front composite transparent conductive film on a side of the semiconductor substrate layer facing away from the back composite transparent conductive film and wherein material of the front composite transparent conductive film comprises tungsten-doped indium oxide.