Transparent conducting oxide for photovoltaic devices

1. A solar cell, comprising:

a Si base layer;

a passivation layer positioned on a first side of the Si base layer;

a p type doped amorphous semiconductor layer positioned on the passivation layer;

a first transparent-conducting-oxide layer positioned on and in direct contact with the p-type doped amorphous semiconductor layer, wherein the first transparent-conducting-oxide layer has a work function that is between 4.9 eV and 6.1 eV, and wherein the first transparent-conducting-oxide layer comprises at least one of: GaInO, GaInSnO, and ZnInO;

a second transparent-conducting-oxide layer comprising indium-tin-oxide positioned on and in direct contact with the first transparent-conducting-oxide layer; and

a first metal grid positioned on a first side of the second transparent-conducting-oxide layer.

2. The solar cell of claim 1 , wherein the solar cell is configured to receive light from the first side of the Si base layer.

3. The solar cell of claim 1 , further comprising a second metal grid positioned on a second side of the Si base layer.

4. The solar cell of claim 3 , wherein the solar cell is configured to receive light from the second side of the Si base layer, and wherein the second metal grid comprises Ag, Cu, and/or Ni.

5. The solar cell of claim 1 , wherein the Si base layer includes a crystalline-Si substrate.

6. The solar cell of claim 1 , wherein the Si base layer includes an epitaxially formed crystalline-Si thin film.

7. The solar cell of claim 1 , wherein the passivation layer includes at least one of: undoped a-Si and SiO x .

8. The solar cell of claim 1 , wherein the p-type doped amorphous semiconductor layer has a doping concentration between 1×10 17 /cm 3 and 5×10 20 /cm 3 .

9. The solar cell of claim 1 , wherein the first metal grid comprises at least one of: Ag, Cu, and Ni.

10. The solar cell of claim 1 , wherein the p-type doped amorphous semiconductor comprises amorphous Si or amorphous Si containing carbon.

11. A method for fabricating a solar cell, comprising:

preparing a Si base layer;

depositing a first passivation layer on a first surface the Si base layer;

depositing a p-type doped amorphous semiconductor layer on the first passivation layer;

depositing a first transparent-conducting-oxide layer, wherein the first transparent-conducting-oxide layer comprises at least one of: GaInO, GaInSnO, and ZnInO; wherein the first transparent-conducting-oxide layer has a work function that is between 4.9 eV and 6.1 eV; and wherein the first transparent conducting-oxide layer is in direct contact with the p-type doped amorphous semiconductor layer;

depositing a second transparent-conducting-oxide layer, wherein the second transparent-conducting-oxide layer comprises indium-tin-oxide and is in direct contact with the first TCO layer; and

forming a first metal grid on a surface of the second transparent-conducting-oxide layer.

12. The method of claim 11 , further comprising:

depositing a second passivation layer on a second surface of the Si base layer;

depositing an n-type doped amorphous semiconductor layer on the second passivation layer;

depositing a third transparent-conducting-oxide layer on the n-type doped amorphous semiconductor layer; and

forming a second metal grid on the third transparent-conducting-oxide layer.

13. The method of claim 11 , wherein preparing the Si base layer involves texturing and cleaning a crystalline-Si substrate.

14. The method of claim 11 , wherein preparing the Si base layer involves epitaxially growing a crystalline-Si layer.

15. The method of claim 11 , wherein the first passivation layer includes at least one of: undoped a-Si and SiO x .

16. The method of claim 11 , wherein the p-type doped amorphous semiconductor layer has a doping concentration between 1×10 17 /cm 3 and 5×10 20 /cm 3 .

17. The method of claim 11 , wherein forming the first metal grid involves electroplating of a layer of Cu and/or a layer of Ni.

18. A solar cell, comprising:

a Si base layer;

a passivation layer positioned on a first side of the Si base layer;

a layer of p-type doped amorphous semiconductor positioned on the passivation layer;

a first transparent-conducting-oxide positioned on and in direct contact with the p-type doped amorphous semiconductor layer, wherein the first transparent-conducting-oxide layer has a work function that is between 4.9 eV and 6.1 eV, and wherein the first TCO layer comprises GaInO or GaInSnO

a second transparent-conducting-oxide layer comprising indium-tin-oxide positioned on and in direct contact with the first transparent-conducting-oxide layer; and

a first metal grid positioned on the second transparent-conducting-oxide layer.