Solar cell and manufacturing method thereof
A solar cell manufacturing method according to this embodiment includes: forming a second photoelectric conversion portion including a semiconductor substrate, a first semiconductor layer on one side of the semiconductor substrate, and a second semiconductor layer having a different conductivity type from the first semiconductor layer on the other side of the semiconductor substrate; forming a junction layer on the first semiconductor layer; changing a surface property of a front surface of the junction layer; forming a first photoelectric conversion portion including a photoelectric conversion layer including a perovskite compound on the front surface of the junction layer; and forming a first electrode electrically connected to the first photoelectric conversion portion on one side of the first photoelectric conversion portion and a second electrode electrically connected to the second photoelectric conversion portion on the other side of the second photoelectric conversion portion. Therefore, in a tandem structure provided with the first photoelectric conversion portion including the perovskite compound and the second photoelectric conversion portion including the semiconductor substrate, an adhesion property can be improved by changing the junction layer between the first photoelectric conversion portion and the second photoelectric conversion portion to hydrophilicity.
1 . A solar cell, comprising:
a photoelectric conversion portion, comprising a first photoelectric conversion portion comprising a photoelectric conversion layer formed of a perovskite compound, and a second photoelectric conversion portion comprising a semiconductor substrate;
a junction layer, formed between the first photoelectric conversion portion and the second photoelectric conversion portion;
a first electrode, electrically connected to the photoelectric conversion portion on one side of the photoelectric conversion portion; and
a second electrode, electrically connected to the photoelectric conversion portion on the other side of the photoelectric conversion portion,
wherein the junction layer comprises a back surface in contact with the second photoelectric conversion portion and a front surface in contact with the first photoelectric conversion portion, and the back surface and the front surface have different surface properties;
wherein the back surface of the junction layer has a hydrophilic surface property and the front surface of the junction layer has a hydrophobic surface property.
2 . The solar cell according to claim 1 , wherein the second photoelectric conversion portion comprises the semiconductor substrate, a first-conductivity-type first semiconductor layer on one side of the semiconductor substrate, and a second-conductivity-type second semiconductor layer on the other side of the semiconductor substrate.
3 . The solar cell according to claim 1 , wherein the junction layer comprises a transparent conductive oxide (TCO) layer that is formed on the first-conductivity-type first semiconductor layer and has a hydrophilic surface property.
4 . The solar cell according to claim 3 , wherein a front surface of the TCO layer of the junction layer is formed by plasma surface treatment to have a hydrophobic surface property.
5 . The solar cell according to claim 3 , wherein the junction layer further comprises an interface layer in contact with the first photoelectric conversion portion on the TCO layer.
6 . The solar cell according to claim 5 , wherein the interface layer comprises a doped semiconductor layer and has a hydrophobic surface property.
7 . The solar cell according to claim 5 , wherein a tunneling layer is further comprised between the semiconductor substrate and the second-conductivity-type second semiconductor layer, and the interface layer is formed to be thinner than the tunneling layer.
8 . The solar cell according to claim 7 , wherein the first photoelectric conversion portion comprises the photoelectric conversion layer formed of the perovskite compound, a first transport layer formed above the photoelectric conversion layer, and a second transport layer formed below the photoelectric conversion layer,
wherein the second transport layer is formed to be bonded to the junction layer, and
the second transport layer has a hydrophobic surface property.
9 . The solar cell according to claim 8 , wherein the second transport layer comprises N-propyl bromide (NPB) or 2,2′,7,7′-tetra(N,N-di-p-tolyl)amino-9,9-spirobifluorene (Spiro-TTB) having a hydrophobic surface property.
10 . The solar cell according to claim 1 , wherein the first photoelectric conversion portion is positioned on one side of the second photoelectric conversion portion,
the first electrode is positioned on the first photoelectric conversion portion,
the second electrode is positioned on the second semiconductor layer of the second photoelectric conversion portion,
the second semiconductor layer comprises a polycrystalline portion, and
laminated structures of the first electrode and the second electrode are different from each other.
11 . A method for manufacturing a solar cell according to claim 1 , comprising:
forming a second photoelectric conversion portion comprising a semiconductor substrate, a first semiconductor layer on one side of the semiconductor substrate, and a second semiconductor layer having a different conductivity type from the first semiconductor layer on the other side of the semiconductor substrate;
forming a junction layer on the first semiconductor layer;
changing a surface property of a front surface of the junction layer;
forming a first photoelectric conversion portion on the front surface of the junction layer, wherein the photoelectric conversion layer comprises a photoelectric conversion layer formed of a perovskite compound; and
forming a first electrode electrically connected to the first photoelectric conversion portion on one side of the first photoelectric conversion portion and a second electrode electrically connected to the second photoelectric conversion portion on the other side of the second photoelectric conversion portion.
12 . The method according to claim 11 , wherein, during forming the junction layer, a TCO layer having a hydrophilic surface property is formed on the first semiconductor layer of the semiconductor substrate.
13 . The method according to claim 12 , wherein, during changing the surface property of the junction layer, a back surface of the junction layer is treated to have a hydrophilic surface property and the front surface of the junction layer is treated to have a hydrophobic surface property.
14 . The method according to claim 13 , wherein, during changing the surface property of the junction layer, a front surface of the TCO layer of the junction layer is subjected to plasma surface treatment to have a hydrophobic surface property.
15 . The method according to claim 14 , wherein the plasma surface treatment is performed with CH 4 plasma or fluorine plasma at a temperature below 200° C.
16 . The method according to claim 13 , wherein the step of changing a surface property of the junction layer further comprises:
a step of forming, on the TCO layer, an interface layer in contact with the first photoelectric conversion portion.
17 . The method according to claim 16 , wherein the forming of an interface layer comprises:
depositing an amorphous silicon layer on the TCO layer; and
injecting a high-concentration dopant to the amorphous silicon layer to change the surface property to hydrophobicity.
18 . The method according to claim 17 , wherein a tunneling layer is further comprised between the semiconductor substrate and the second semiconductor layer, and the interface layer is formed to be thinner than the tunneling layer.
19 . The method according to claim 13 , wherein the first photoelectric conversion portion is formed to comprise the photoelectric conversion layer formed of the perovskite compound, a first transport layer formed above the photoelectric conversion layer, and a second transport layer formed below the photoelectric conversion layer,
wherein the second transport layer is formed to be in contact with the junction layer, and
the second transport layer is formed by depositing a material having a hydrophobic surface property.