Multilayer light scattering photovoltaic back reflector and method of making same

• US 5,101,260 A
• Filed: 11/05/1990
• Issued: 03/31/1992
• Est. Priority Date: 05/01/1989
• Status: Expired due to Term

• Current Assignee: United Solar Systems Corp.
• Original Assignee: Energy Conversion Devices
• Inventors: Laarman, Timothy D., Call, John, DiDio, Gary, Nath, Prem, Hoffman, Kevin
• Primary Examiner(s): James, Andrew J.
• Assistant Examiner(s): Meier, Stephen D.
• Application Number:
  US07/609,040
• Time in Patent Office: 512 Days
• Field of Search: 357/30, 357/67, 357/71, 357/62, 357/65
• US Class Current: 257/53
• CPC Class Codes: H01L 31/0236 Special surface textures
• CPC Class Codes: H01L 31/02366 of the substrate or of a layer on the substrate, e.g. textured ITO/glass substrate or superstrate, textured polymer layer on glass substrate
• CPC Class Codes: H01L 31/056 the light-reflecting means being of the back surface reflector [BSR] type
• CPC Class Codes: Y02E 10/52 PV systems with concentrators

Abstract

A multilayered, light-scattering back reflector for a photovoltaic device, said back reflector including a first relatively hard, textured layer atop a substrate and a second highly reflective layer conformally disposed atop the first layer. The back reflector may further include a third light scattering layer formed atop said second layer, said third layer adapted to further provide a barrier layer between the body of semiconductor material from which the photovoltaic device is formed and the multilayered back reflector.

Claims

1. In a photoresponsive device, which device includes a substrate, a light scattering back reflector atop said substrate, and a multilayered body of semiconductor material atop said back reflector, the improvement comprising, in combination:

said back reflector comprising a tri-layered body including a hard, textured, non-highly reflective layer formed of a material other than copper, aluminum or silver and disposed directly upon said substrate, said textured layer having substantially micro-sized features;

a highly reflective layer conformally disposed atop said textured layer; and

a transparent oxide layer deposited upon said highly reflective layer, said oxide layer adapted to enhance light scattering and optical coupling.

2. A device as in claim 1, wherein said third transparent oxide layer is an electrically conductive transparent oxide material.

3. A device as in claim 1, wherein said relatively hard, textured layer is formed of a material selected from the group consisting essentially of aluminum, aluminum alloys, copper, copper alloys, and combinations thereof.

4. A device as in claim 1, wherein said reflective layer is formed of silver.

5. A device as in claim 2, wherein said transparent oxide layer is formed of a material selected from the group consisting essentially of zinc oxide, tin oxide, indium oxide, indium tin oxide, cadmium stannate, and combination thereof.

6. A device as in claim 1, wherein said hard, textured layer is approximately 1500-3000 Angstroms thick.

7. A device as in claim 1, wherein said reflective layer is approximately 200-500 Angstroms thick.

8. A device as in claim 1, wherein aid transparent oxide layer is approximately 1000-5000 Angstroms thick.

9. A device as in claim 1, wherein said photoresponsive device is a photovoltaic device including at least one p-i-n type cell formed of amorphous silicon alloy material.

10. A device as in claim 1, wherein said substrate is electrically conductive and formed from a material selected from the group consisting essentially of stainless steel, nickel, aluminum, and combinations thereof.

11. A device as in claim 1, wherein said substrate is electrically insulating and further includes an electrically conductive layer operatively disposed between said substrate and said back reflector;

said insulating substrate formed of a material selected from the group consisting essentially of polyimide, glass and combinations thereof.

12. A device as in claim 1, wherein the texturing of said relatively hard, textured layer is formed by mechanical means.