Monolithic multi-junction solar cells with amorphous silicon and CIS and their alloys

• US 6,368,892 B1
• Filed: 06/29/2000
• Issued: 04/09/2002
• Est. Priority Date: 07/28/1997
• Status: Expired due to Fees

• Current Assignee: BP Solar International LLC (BP PLC)
• Original Assignee: BP Corporation North America Incorporated (BP PLC)
• Inventors: Arya, Rajeewa R.
• Primary Examiner(s): Dye, Rena L.
• Assistant Examiner(s): Miggins, Michael C.
• Application Number:
  US09/606,298
• Time in Patent Office: 649 Days
• Field of Search: 136/255, 136/258, 136/261, 136/262, 136/264, 136/249, 438/93, 438/94, 438/95, 438/96, 438/74, 438/84, 438/86, 257/461, 257/187, 257/200
• US Class Current: 438/96
• CPC Class Codes: H01L 31/0322 comprising only AIBIIICVI chalcopyrite compounds, e.g. Cu In Se2, Cu Ga Se2, Cu In Ga Se2
• CPC Class Codes: H01L 31/078 including different types of potential barriers provided for in two or more of groups H01L31/062 - H01L31/075
• CPC Class Codes: Y02E 10/541 CuInSe2 material PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Efficient broader spectrum monolithic solar cells are produced by coupling a CIS or CIGS polycrystalline semiconductor to an amorphous silicon semiconductor. Coupling can be accomplished with a n-type conductor, such as cadmium sulfide or microcrystalline n-duped amorphous silicon. Cadmium sulfide can be deposited on the CIS or CIGS polycrystalline semiconductor by solution growth, sputtering or evaporation. A transparent conductive oxide can be deposited on the cadmium sulfide by low pressure chemical vapor deposition. The microcrystalline n-doped amorphous silicon and the amorphous silicon semiconductor can be deposited by enhanced plasma chemical vapor deposition. The amorphous silicon can comprise: hydrogenated amorphous silicon, hydrogenated amorphous silicon carbon, or hydrogenated amorphous silicon germanium. Triple junction solar cells can be produced with an amorphous silicon front cell, an amorphous silicon germanium middle cell, and a CIS or CIGS polycrystalline back cell, on a substrate.

Claims

1. A process for producing monolithic solar cells, comprising the steps of:

coupling an amorphous silicon thin film semiconductor to a copper indium polycrystalline semiconductor by

depositing said copper indium polycrystalline semiconductor on a substrate selected from the group consisting of a vitreous substrate and a metal substrate;

depositing an n-type conductor on said polycrystalline semiconductor; and

depositing said amorphous silicon thin film semiconductor on said n-type conductor wherein said amorphous thin film semiconductor comprises one or more of a p-i-n or n-i-p amorphous silicon-containing thin film semiconductor.

2. A process for producing monolithic solar cells in accordance with claim 1 wherein said copper indium polycrystalline semiconductor is deposited by evaporation and contains 0% to 24% by weight gallium.

3. A process for producing monolithic solar cells in accordance with claim 2 wherein:

said copper indium polycrystalline semiconductor is selected from the group consisting of CIS and CIGS;

said vitreous substrate comprises glass; and

said metal substrate is selected from the group consisting of steel, iron, aluminum, niobium, titanium, chromium, bismuth and antimony.

4. A process for producing monolithic solar cells in accordance with claim 1 including:

positioning a rear contact on said substrate before depositing said copper indium polycrystalline semiconductor, said rear contact being selected from the group consisting of molybdenum, aluminum, silver, platinum, zinc oxide, and tin oxide; and

positioning a front contact on said amorphous silicon thin film semiconductor, and said front contact comprising a transparent conductive oxide selected from the group consisting of zinc oxide and tin oxide.

5. A process for producing monolithic solar cells in accordance with claim 1 wherein said n-type conductor comprises cadmium sulfide and said n-type conductor is deposited by a method selected from the group consisting of solution growth, sputtering and evaporation.

6. A process for producing monolithic solar cells in accordance with claim 5 wherein:

a transparent conductive oxide is deposited on said cadmium sulfide by low pressure chemical vapor deposition; and

said transparent conductive oxide is selected from the group consisting of tin oxide and zinc oxide.

7. A process for producing monolithic solar cells in accordance with claim 1 wherein said n-type conductor comprises microcrystalline n-doped amorphous silicon and said n-type conductor is deposited by enhanced plasma chemical vapor deposition.

8. A process for producing monolithic solar cells in accordance with claim 1 wherein said amorphous thin film semiconductor is a single junction cell.

9. A process for producing monolithic solar cells in accordance with claim 1 wherein said process includes:

producing monolithic solar cells in the absence of a glass superstrate and a metal superstrate; and

said monolithic solar cells are selected from the group consisting of multi-junction solar cells, tandem solar cells, and triple junction solar cells.

10. A process for producing monolithic solar cells in accordance with claim 1 wherein:

said amorphous silicon thin film semiconductor is deposited by enhanced plasma chemical vapor deposition;

said amorphous silicon thin film semiconductor is selected from the group consisting of hydrogenated amorphous silicon, hydrogenated amorphous silicon germanium, hydrogenated amorphous silicon carbon, and combinations thereof; and

said amorphous silicon thin film semiconductor comprises a p-i-n or an n-i-p semiconductor.

11. A process for producing monolithic solar cells in accordance with claim 1 wherein said process includes producing triple junction solar cells by

depositing an amorphous silicon germanium semiconductor on said n-type conductor;

and

depositing an amorphous silicon semiconductor on said amorphous silicon germanium semiconductor.

12. A process for producing multi-junction monolithic solar cells, comprising the steps of:

placing a rear contact selected from the group consisting of molybdenum, aluminum, silver, platinum, tin oxide, and zinc oxide, on a substrate selected from the group consisting of glass, metal, and stainless steel;

depositing a polycrystalline back cell having a bandgap ranging from about 1 eV to about 1.2 eV on said rear contact placed on said substrate, said polycrystalline back cell being selected from the group consisting of copper indium diselenide (CIS) and copper indium gallium selemide (CIGS), and said copper indium gallium selenide comprising 0.1 to 24% by weight gallium;

depositing an n-type conductor selected from the group consisting of cadmium sulfide and microcrystalline n-type amorphous silicon, on said polycrystalline back cell;

depositing an amorphous silicon front cell having a bandgap ranging from about 1.4 eV to about 1.6 eV on top of said n-type conductor, said amorphous silicon front cell being selected from the group consisting of hydrogenated amorphous silicon, hydrogenated amorphous silicon carbon, and hydrogenated amorphous silicon germanium; and

placing and depositing a front contact comprising transparent conductive oxide selected from the group consisting of zinc oxide and tin oxide, on said front cell.

13. A process for producing multi-junction monolithic solar cells in accordance with claim 12 wherein said polycrystalline back cell is deposited by evaporation at a temperature ranging from about 400°

C. to about 500°

C.

14. A process for producing multi-junction monolithic solar cells in accordance with claim 12 wherein said n-type conductor comprises cadmium sulfide and said n-type conductor is deposited by a method selected from the group consisting of solution growth, sputtering and evaporation.

15. A process for producing multi-junction monolithic solar cells in accordance with claim 14 wherein:

a transparent conductive oxide is deposited on said cadmium sulfide by low pressure chemical vapor deposition; and

said transparent conductive oxide is selected from the group consisting of tin oxide and zinc oxide.

16. A process for producing multi-junction monolithic solar cells in accordance with claim 12 wherein said n-type conductor comprises microcrystalline n-doped amorphous silicon and said n-type conductor is deposited by enhanced plasma chemical vapor deposition.

17. A process for producing multi-junction monolithic solar cells in accordance with claim 12 wherein said amorphous silicon front cell is deposited by enhanced plasma chemical vapor deposition at a temperature ranging from about 180°

C. to about 200°

C.

18. A process for producing multi-junction monolithic solar cells in accordance with claim 12 wherein said process includes:

producing triple junction monolithic solar cells by

depositing an amorphous silicon intermediate middle cell on said n-type conductor by enhanced plasma chemical vapor deposition, said amorphous silicon intermediate middle cell having a bandgap ranging from about 1.4 eV to about 1.6 eV and comprising hydrogenated amorphous silicon germanium; and

depositing said amorphous silicon front cell on said amorphous silicon intermediate middle cell by enhanced plasma chemical vapor deposition, said amorphous silicon front cell comprising having a bandgap of about 1.4 eV and comprising hydrogenated amorphous silicon.

19. A process for producing solar cells comprising the steps of:

depositing a copper indium polycrystalline semiconductor layer;

depositing an n-type conductor comprising one or more selected from the group consisting of cadmium sulfide and microcrystalline n-doped amorphous silicon; and

depositing an amorphous silicon thin film semiconductor.