TUNNELING-JUNCTION SOLAR CELL WITH COPPER GRID FOR CONCENTRATED PHOTOVOLTAIC APPLICATION

• US 20150236177A1
• Filed: 05/04/2015
• Published: 08/20/2015
• Est. Priority Date: 06/02/2011
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: SolarCity Corporation (Tesla Inc.)
• Inventors: Fu, Jianming, Xu, Zheng, Heng, Jiunn Benjamin, Yu, Chentao
• Granted Patent: US 9,887,306 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 31/022425 for solar cells
• CPC Class Codes: H01L 31/022433 Particular geometry of the grid contacts
• CPC Class Codes: H01L 31/035209 comprising a quantum structures
• CPC Class Codes: H01L 31/054 Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means
• CPC Class Codes: H01L 31/0747 comprising a heterojunction of crystalline and amorphous materials, e.g. heterojunction with intrinsic thin layer
• CPC Class Codes: H01L 31/1804 comprising only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/1884 Manufacture of transparent electrodes, e.g. TCO, ITO
• CPC Class Codes: Y02E 10/52 PV systems with concentrators
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

One embodiment of the present invention provides a photovoltaic module. The photovoltaic module includes an optical concentrator and a tunneling-junction solar cell. The tunneling-junction solar cell includes a base layer, a quantum-tunneling-barrier (QTB) layer situated above the base layer, an emitter layer, a front-side electrode, and a back-side electrode.

Claims

1. A solar cell, comprising:

a crystalline silicon base layer;

a first dielectric quantum-tunneling-barrier layer in direct contact with a first side of the base layer;

a first doped silicon layer having a band gap greater than a band gap of the base layer and positioned adjacent to the first dielectric quantum-tunneling-barrier layer;

a first electrode electrically coupled to the first doped silicon layer;

a second dielectric quantum-tunneling-barrier layer in direct contact with a second side of the base layer;

a second doped silicon layer having a band gap greater than the band gap of the base layer and positioned adjacent to the second dielectric quantum-tunneling-barrier layer; and

a second electrode electrically coupled to the second doped silicon layer.

2. The solar cell of claim 1, wherein the first and second quantum-tunneling-barrier layers comprise at least one of:

silicon oxide (SiO_x);

hydrogenated SiO_x;

silicon nitride (SiN_x);

hydrogenated SiN_x;

aluminum oxide (AlO_x);

silicon oxynitride (SiON); and

hydrogenated SiON.

3. The solar cell of claim 1, wherein the first and second doped silicon layers comprise at least one of:

amorphous silicon;

nanocystalline silicon;

protocrystalline silicon; and

amorphous silicon carbide.

4. The solar cell of claim 1, wherein the first electrode and second electrode each include a metal grid, which comprises Cu.

5. The solar cell of claim 4, wherein the metal grid is formed using a plating technique;

and

wherein the metal grid further comprises a barrier layer between Cu and the rest of the solar cell.

6. The solar cell of claim 1, wherein at least one of the first and second electrodes includes a metal grid line having a curved surface, thereby allowing light incident upon the curved surface to be reflected toward the solar cell.

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

a first transparent conductive oxide layer positioned between the first doped silicon layer and the first electrode; and

a second transparent conductive oxide layer positioned between the second doped silicon layer and the second electrode.

8. The solar cell of claim 1, wherein the crystalline silicon base layer is n-type doped;

wherein the first doped silicon layer is n-type doped and functions as a surface field layer; and

wherein the second doped silicon layer is p-type doped and functions as an emitter layer.

9. The solar cell of claim 1, wherein the first side of the crystalline silicon base layer is configured to face the sun.

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

forming a first dielectric quantum-tunneling-barrier layer on a first side of a crystalline silicon base layer;

forming a first doped silicon layer adjacent to the first dielectric quantum-tunneling-barrier layer, the first doped silicon layer'"'"'s band gap being greater than a band gap of the base layer and positioned;

forming a first electrode that is electrically coupled to the first doped silicon layer;

forming a second dielectric quantum-tunneling-barrier layer on a second side of the base layer;

forming a second doped silicon layer adjacent to the second dielectric quantum-tunneling-barrier layer, the second doped silicon layer'"'"'s band gap being greater than the band gap of the base layer and positioned; and

forming a second electrode that is electrically coupled to the second doped silicon layer.

11. The method of claim 10, wherein the first and second quantum-tunneling-barrier layers comprise at least one of:

silicon oxide (SiO_x);

hydrogenated SiO_x;

silicon nitride (SiN_x);

hydrogenated SiN_x;

aluminum oxide (AlO_x);

silicon oxynitride (SiON); and

hydrogenated SiON.

12. The method of claim 10, wherein the first and second doped silicon layers comprise at least one of:

amorphous silicon;

nanocystalline silicon;

protocrystalline silicon; and

amorphous silicon carbide.

13. The method of claim 10, wherein forming the first electrode and second electrode comprises forming a metal grid that comprises Cu.

14. The method of claim 13, wherein forming the metal grid comprises using a plating technique;

and

wherein the metal grid further comprises a barrier layer between Cu and the rest of the solar cell.

15. The method of claim 10, wherein forming the first and second electrodes comprises forming a metal grid line having a curved surface, thereby allowing light incident upon the curved surface to be reflected toward the solar cell.

16. The method of claim 10, further comprising:

forming a first transparent conductive oxide layer positioned between the first doped silicon layer and the first electrode; and

forming a second transparent conductive oxide layer positioned between the second doped silicon layer and the second electrode.

17. The method of claim 10, wherein the crystalline silicon base layer is n-type doped;

wherein the first doped silicon layer is n-type doped and functions as a surface field layer; and

wherein the second doped silicon layer is p-type doped and functions as an emitter layer.

18. The method of claim 10, wherein the first side of the crystalline silicon base layer is configured to face the sun.

19. A photovoltaic module, comprising:

an optical concentrator; and

a solar cell, which comprises;

a crystalline silicon base layer;

a first dielectric quantum-tunneling-barrier layer in direct contact with a first side of the base layer;

a first doped silicon layer having a band gap greater than a band gap of the base layer and positioned adjacent to the first dielectric quantum-tunneling-barrier layer;

a first electrode electrically coupled to the first doped silicon layer;

a second dielectric quantum-tunneling-barrier layer in direct contact with a second side of the base layer;

a second doped silicon layer having a band gap greater than the band gap of the base layer and positioned adjacent to the second dielectric quantum-tunneling-barrier layer; and

a second electrode electrically coupled to the second doped silicon layer.