ALUMINUM PASTES AND USE THEREOF IN THE PRODUCTION OF SILICON SOLAR CELLS

• US 20090255583A1
• Filed: 04/09/2009
• Published: 10/15/2009
• Est. Priority Date: 04/15/2008
• Status: Abandoned Application

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Young, Richard John Sheffield, Prince, Alistair Graeme
• Application Number:
  US12/420,911
• Publication Number:
  US 20090255583A1
• Time in Patent Office: Days
• US Class Current: 136/261
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H01L 31/022425 for solar cells
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

Aluminum pastes comprising particulate aluminum, a tin-organic component and an organic vehicle and their use in forming p-type aluminum back electrodes of silicon solar cells.

Claims

1. Aluminum paste comprising particulate aluminum, a tin-organic component and an organic vehicle comprising organic solvent(s).

2. The aluminum paste of claim 1 additionally comprising one or more glass frits in a total proportion of 0.01 to 5 wt. %, based on total aluminum paste composition.

3. The aluminum paste of claim 1 additionally comprising a zinc-organic component in a proportion corresponding to a zinc contribution of 0.05 to 0.6 wt. %, based on total aluminum paste composition.

4. The aluminum paste of claim 1 additionally comprising amorphous silicon dioxide in a proportion of above 0 to 0.5 wt. %, based on total aluminum paste composition.

5. The aluminum paste of claim 1, wherein the particulate aluminum is present in a proportion of 50 to 80 wt. %, based on total aluminum paste composition.

6. The aluminum paste of claim 1, wherein the tin-organic component is selected from the group consisting of one solid tin-organic compound, a combination of two or more solid tin-organic compounds, one liquid tin-organic compound, a combination of two or more liquid tin-organic compounds, a combination of solid and liquid tin-organic compounds and a solution of one or more tin-organic compounds in organic solvent(s).

7. The aluminum paste of claim 6, wherein the tin-organic component is present in a proportion corresponding to a tin contribution of 0.01 to 0.5 wt. %, based on total aluminum paste composition.

8. The aluminum paste of claim 6, wherein the tin-organic compound(s) is/are tin-organic salt compounds selected from the group consisting of tin resinates and tin carboxylates.

9. The aluminum paste of claim 6, wherein the tin-organic component is tin(II) 2-ethylhexanoate being present in a proportion of 0.1 to 1 wt. %, based on total aluminum paste composition.

10. The aluminum paste of claim 1, wherein the organic vehicle further comprises organic polymer(s) and/or organic additive(s).

11. A process of forming a silicon solar cell comprising the steps:

(i) applying an aluminum paste of claim 1 on the back-side of a silicon wafer having a p-type region, an n-type region and a p-n junction, and

(ii) firing the surface provided with the aluminum paste, whereby the wafer reaches a peak temperature of 700 to 900°

C.

12. The process of claim 11, wherein the application of the aluminum paste is performed by printing.

13. The process of claim 11, wherein firing is performed as cofiring together with other front-side and/or back-side metal pastes that have been applied to the silicon wafer to form front-side and/or back-side electrodes thereon during firing.

14. Silicon solar cells made by the process of claim 11.

15. A silicon solar cell comprising an aluminum back electrode wherein the aluminum back electrode is produced making use of an aluminum paste of claim 1.

16. The silicon solar cell of claim 15, further comprising a silicon wafer.