Front electrode for use in photovoltaic device and method of making same

• US 20090084438A1
• Filed: 09/19/2008
• Published: 04/02/2009
• Est. Priority Date: 11/02/2006
• Status: Active Grant

• Current Assignee: Guardian Glass LLC (KOCH Industries Incorporated)
• Original Assignee: Guardian Industries Corporation (KOCH Industries Incorporated)
• Inventors: Broadway, David, Corsner, Bryce, Lu, Yiwei, den Boer, Willem
• Granted Patent: US 8,076,571 B2
• Time in Patent Office: Days
• US Class Current: 136/256
• CPC Class Codes: H01L 31/02168 the coatings being antireflective or having enhancing optical properties for the solar cells
• CPC Class Codes: H01L 31/022466 made of transparent conductive layers, e.g. TCO, ITO layers
• CPC Class Codes: H01L 31/022475 composed of indium tin oxide [ITO]
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

This invention relates to a front electrode/contact for use in an electronic device such as a photovoltaic device. In certain example embodiments, the front electrode of a photovoltaic device or the like includes a multilayer coating including at least one transparent conductive oxide (TCO) layer (e.g., of or including a material such as tin oxide, ITO, zinc oxide, or the like) and/or at least one conductive substantially metallic IR reflecting layer (e.g., based on silver, gold, or the like). In certain example instances, the multilayer front electrode coating may include one or more conductive metal(s) oxide layer(s) and/or one or more conductive substantially metallic IR reflecting layer(s) in order to provide for reduced visible light reflection, increased conductivity, cheaper manufacturability, and/or increased infrared (IR) reflection capability.

Claims

1. A photovoltaic device including a front electrode structure, the front electrode structure comprising:

a front substantially transparent glass substrate;

a dielectric layer comprising titanium oxide;

a dielectric layer comprising silicon oxynitride, wherein the layer comprising titanium oxide is located between the glass substrate and the layer comprising silicon nitride;

a conductive layer comprising indium tin oxide, wherein the layer comprising silicon oxynitride is located between at least the layer comprising indium tin oxide and the layer comprising titanium oxide;

a conductive layer comprising zinc oxide and/or zinc aluminum oxide;

wherein the front electrode structure comprising said layer comprising titanium oxide, said layer comprising silicon oxynitride, said conductive layer comprising indium tin oxide, and said conductive layer comprising zinc oxide and/or zinc aluminum oxide is provided on an interior surface of the front glass substrate facing a semiconductor film of the photovoltaic device.

2. The photovoltaic device of claim 1, further comprising another layer comprising silicon oxynitride and/or silicon nitride between the glass substrate and the layer comprising titanium oxide.

3. The photovoltaic device of claim 1, wherein an exterior surface of the glass substrate is etched, but the interior surface of the glass substrate on which the layer stack is provided is not etched and is substantially flat.

4. The photovoltaic device of claim 1, wherein the semiconductor film comprises silicon, and the front electrode structure has a transmission of at least 85% in at least a majority of a range of from 450-700 nm.

5. The photovoltaic device of claim 1, wherein the semiconductor film comprises silicon, and the front electrode structure has a transmission of at least 87% in at least part of a range of from 450-700 nm.

6. The photovoltaic device of claim 1, wherein the semiconductor film comprises CdS and/or CdTe, and the front electrode structure has a transmission of at least 90% in at least a majority of a range of from 500-600 nm.

7. The photovoltaic device of claim 1, wherein the semiconductor film comprises CdS and/or CdTe, and the front electrode structure has a transmission of at least 92% in at least part of a range of from 500-600 nm.

8. A photovoltaic device including a front electrode structure, the front electrode structure comprising:

a front substantially transparent glass substrate;

a dielectric layer comprising silicon oxynitride,

a dielectric layer comprising titanium oxide, wherein the layer comprising silicon oxynitride is located between the glass substrate and the layer comprising titanium oxide;

a conductive film comprising indium tin oxide and/or silver, wherein the layer comprising titanium oxide is located between the layer comprising indium tin oxide and/or silver and the layer comprising silicon oxynitride;

wherein the front electrode structure comprising said layer comprising silicon oxynitride, the layer comprising titanium oxide, and said film comprising indium tin oxide and/or silver is provided on an interior surface of the front glass substrate facing a semiconductor film of the photovoltaic device.

9. The photovoltaic device of claim 8, wherein the dielectric layer comprising silicon oxynitride is an oxidation graded film that is oxidation graded continuously or discontinuously so as to be more oxided closer to the glass substrate and less oxided or not oxided at all at a portion thereof closest to the layer comprising titanium oxide.

10. The photovoltaic device of claim 9, wherein the layer comprising silicon oxynitride includes a layer of silicon nitride closest to the layer comprising titanium oxide and a layer comprising silicon oxynitride closest to the glass substrate.

11. A photovoltaic device including a front electrode structure, the front electrode structure comprising:

a front substantially transparent glass substrate;

a first layer comprising silicon nitride;

a second layer comprising titanium oxide, wherein at least the first layer is located between the front substrate and the second layer;

a third layer comprising zinc oxide and/or zinc aluminum oxide;

a conductive layer comprising silver, wherein at least the third layer is provided between the conductive layer comprising silver and the second layer;

a layer comprising Ni and/or Cr;

a transparent conductive oxide (TCO) film located between the layer comprising Ni and/or Cr and a semiconductor film of the photovoltaic device; and

wherein a layer stack comprising said first layer, said second layer, said third layer, said conductive layer comprising silver, and said layer comprising Ni and/or Cr is provided on an interior surface of the front glass substrate facing the semiconductor film of the photovoltaic device.

12. The photovoltaic device of claim 11, wherein an exterior surface of the glass substrate is etched, but the interior surface of the glass substrate on which the layer stack is provided is not etched and is substantially flat.

13. The photovoltaic device of claim 11, wherein the front electrode structure acts not only as a front electrode for the photovoltaic device, but also as a short pass filter that (i) allows a large amount of photons having energy in the visible and near-IR regions into the semiconductor film, and (ii) blocks significant amounts of other IR radiation from reaching the semiconductor film.

14. The photovoltaic device of claim 13, wherein the semiconductor film comprises a-Si, and the front electrode structure has a transmission of at least 85% in at least a majority of a range of from 450-700 nm.

15. The photovoltaic device of claim 13, wherein the semiconductor film comprises a-Si, and the front electrode structure has a transmission of at least 87% in at least part of a range of from 450-700 nm.

16. The photovoltaic device of claim 13, wherein the semiconductor film comprises CdS and/or CdTe, and the front electrode structure has a transmission of at least 90% in at least a majority of a range of from 500-600 nm.

17. The photovoltaic device of claim 13, wherein the semiconductor film comprises CdS and/or CdTe, and the front electrode structure has a transmission of at least 92% in at least part of a range of from 500-600 nm.

18. The photovoltaic device of claim 11, wherein the semiconductor film comprises a layer comprising CdS and a layer comprising CdTe.

19. The photovoltaic device of claim 11, wherein the conductive layer comprising silver is from about 3 to 9 nm thick.