SOLAR CELL WITH METAL GRID FABRICATED BY ELECTROPLATING

1 . A solar cell, comprising:

a photovoltaic structure;

a transparent-conductive-oxide (TCO) layer situated above the photovoltaic structure, wherein the TCO layer is in contact with the front surface of the photovoltaic structure; and

a front-side metal grid situated above the TCO layer, wherein the metal grid includes at least one of: Cu and Ni.

2 . The solar cell of claim 1 , wherein the photovoltaic structure includes at least one of:

a homogeneous junction;

a heterojunction;

a heterotunneling junction; and

multiple p-n junctions.

3 . The solar cell of claim 1 , wherein the resistivity of the front-side metal grid is less than 2×10 −5 Ω·cm.

4 . The solar cell of claim 1 , wherein the front-side metal grid further comprises one or more of: Sn and Ag.

5 . The solar cell of claim 1 , wherein the front-side metal grid is formed using an electroplating technique.

6 . The solar cell of claim 1 , wherein the TCO layer comprises at least one of:

indium-tin-oxide (ITO);

aluminum-doped zinc-oxide (ZnO:Al);

gallium-doped zinc-oxide (ZnO:Ga);

tungsten-doped indium oxide (IWO); and

Zn—In—Sn—O (ZITO).

7 . The solar cell of claim 1 , wherein the photovoltaic structure includes at least one of:

a layer of heavily doped amorphous-Si (a-Si);

a layer of intrinsic a-Si;

an a-Si layer with graded doping; and

a layer of silicon oxide in contact with a crystalline silicon (c-Si) substrate.

8 . The solar cell of claim 1 , further comprising a back-side electrode which includes a metal grid which can be connected lines or a continuous layer.

9 . The solar cell of claim 8 , wherein the back-side metal grid is formed using at least one of the following techniques:

screen-printing;

electroplating;

physical vapor deposition including evaporation and sputtering deposition; and

aerosol-jet printing.

10 . The solar cell of claim 1 , further comprising:

a back-side TCO layer situated on the back side of the photovoltaic structure, wherein the back-side TCO layer is in contact with the back surface of the photovoltaic structure; and

a back-side metal grid situated on the back-side TCO layer, wherein the metal grid includes at least one of: Cu and Ni.

11 . The solar cell of claim 10 , further comprising a metal-adhesive layer situated between the back-side TCO layer and the back-side metal grid, wherein the metal-adhesive layer includes at least one of: Cu, Ni, Ag, Ti, Ta, W, NiV, TiN, TaN, WN, TiW, and NiCr.

12 . The solar cell of claim 1 , further comprising a metal-adhesive layer situated between the TCO layer and the front-side metal grid.

13 . The solar cell of claim 12 , wherein the metal-adhesive layer includes at least one of:

Cu, Ni, Ag, Ti, Ta, W, NiV, TiN, TaN, WN, TiW, and NiCr.

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

depositing one or more layers of amorphous-Si (a-Si) on top of a crystalline Si (c-Si) substrate with thin oxide formed on the surface to form a photovoltaic structure;

depositing a layer of transparent-conductive-oxide (TCO) on top of the a-Si layers;

forming a front-side electrode grid comprising a metal stack on top of the TCO layer, wherein the metal stack includes at least one of: a layer of Cu and a layer of Ni; and

forming a back-side electrode on the back side of the Si substrate.

15 . The method of claim 14 , wherein the a-Si layers includes at least one of:

a layer of heavily doped a-Si;

a layer of intrinsic a-Si; and

an a-Si layer with graded doping.

16 . The method of claim 14 , wherein the resistivity of the front-side electrode grid is less than 2×10 −5 Ω·cm.

17 . The method of claim 14 , wherein the metal stack further comprises one or more of:

a layer of Sn; and

a layer of Ag.

18 . The method of claim 14 , wherein forming the front-side electrode grid involves electroplating the metal stack on top of the TCO layer.

19 . The method of claim 18 , wherein forming the front-side electrode grid further involves depositing and/or removing a patterned masking layer on top of the TCO layer.

20 . The method of claim 14 , wherein the TCO layer comprises at least one of:

indium-tin-oxide (ITO);

aluminum-doped zinc-oxide (ZnO:Al);

gallium-doped zinc-oxide (ZnO:Ga);

tungsten-doped indium oxide (IWO); and

Zn—In—Sn—O (ZITO).

21 . The method of claim 14 , wherein the photovoltaic structure includes at least one of:

a homogeneous junction;

a heterojunction;

a heterotunneling junction; and

multiple p-n junctions.

22 . The method of claim 21 , wherein the c-Si substrate is n-type doped, and wherein the heavily doped a-Si layer and/or the a-Si layer with graded doping are p-type doped.

23 . The method of claim 14 , wherein the back-side electrode comprises a metal grid which can be connected lines or a continuous layer.

24 . The method of claim 23 , wherein the back-side metal grid is formed using at least one of the following techniques:

screen-printing;

electroplating;

physical vapor deposition including evaporation and sputtering deposition; and

aerosol-jet printing.

25 . The method of claim 14 , further comprising:

depositing a back-side TCO layer on the back side of the photovoltaic structure, wherein the back-side TCO layer is in contact with the back surface of the photovoltaic structure; and

fabricating a back-side electrode grid on the back-side TCO layer, wherein the back-side electrode grid includes at least one of: Cu and Ni.

26 . The method of claim 25 , further comprising depositing a metal adhesive layer between the back-side TCO layer and the back-side electrode grid, wherein the metal-adhesive layer includes at least one of: Cu, Ni, Ag, Ti, Ta, W, NiV, TiN, TaN, WN, TiW, and NiCr.

27 . The method of claim 14 , further comprising depositing a metal-adhesive layer between the TCO layer and the front-side electrode grid.

28 . The method of claim 27 , wherein the adhesive-metal layer is deposited using a physical vapor deposition technique including one of:

evaporation and sputtering deposition.

29 . The method of claim 27 , wherein the metal-adhesive layer includes at least one of:

Cu, Ni, Ag, Ti, Ta, W, NiV, TiN, TaN, WN, TiW, and NiCr.