Photovoltaic device including front electrode having titanium oxide inclusive layer with high refractive index

• US 20090126791A1
• Filed: 11/20/2007
• Published: 05/21/2009
• Est. Priority Date: 11/20/2007
• Status: Active Grant

• Current Assignee: Guardian Glass LLC (KOCH Industries Incorporated)
• Original Assignee: Guardian Industries Corporation (KOCH Industries Incorporated)
• Inventors: Lu, Yiwei, den Boer, Willem, Krasnov, Alexey
• Granted Patent: US 7,888,594 B2
• Time in Patent Office: Days
• US Class Current: 136/258
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10174 Coatings of a metallic or dielectric material on a constituent layer of glass or polymer
• CPC Class Codes: H01L 31/022466 made of transparent conductive layers, e.g. TCO, ITO layers
• CPC Class Codes: H01L 31/022483 composed of zinc oxide [ZnO]
• CPC Class Codes: H01L 31/0296 including, apart from doping material or other impurities, only AIIBVI compounds, e.g. CdS, ZnS, HgCdTe
• CPC Class Codes: H01L 31/03762 including only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/048 Encapsulation of modules
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells

Abstract

Certain example embodiments of this invention relate to an electrode (e.g., front electrode) for use in a photovoltaic device or the like. In certain example embodiments, a transparent conductive oxide (TCO) of the front electrode for use in a photovoltaic device is of or includes titanium oxide doped with one or more of Nb, Zn and/or Al. Additional layers may also be provided in the front electrode in certain example embodiments. It has been found that the use of transparent conductive TiO_x(:Nb) or TiZnO_x(:Al and/or Nb), in a front electrode of a photovoltaic device, is advantageous in that such materials have a high refractive index (n) and have a higher transparency than conventional titanium suboxide (TiO_x). Thus, the use of such materials in the context of a front electrode of a photovoltaic device reduces light reflection due to the high refractive index, and increases transmission into the active semiconductor film due to the higher transmission characteristics thereof, thereby improving the efficiency of the device.

Claims

1. A photovoltaic device comprising:

a front substrate;

a front electrode;

a semiconductor film, wherein the front electrode is located between at least the front substrate and the semiconductor film; and

wherein the front electrode of the photovoltaic device comprises a first conductive layer and a second conductive layer, wherein the second conductive layer is located between at least the first conductive layer and the semiconductor film, and wherein the second conductive layer comprises titanium zinc oxide doped with aluminum and/or niobium.

2. The photovoltaic device of claim 1, wherein the titanium zinc oxide is doped with from about 0.01 to 10% Al and/or Nb.

3. The photovoltaic device of claim 1, wherein the titanium zinc oxide is doped with from about 0.02 to 7% Al and/or Nb.

4. The photovoltaic device of claim 1, wherein the titanium zinc oxide is doped with from about 0.1 to 5% Al and/or Nb.

5. The photovoltaic device of claim 1, further comprising:

a first layer comprising one or more of silicon nitride, silicon oxide, silicon oxynitride, and/or tin oxide;

a second layer comprising one or more of titanium oxide and/or niobium oxide, wherein at least the first layer is located between the front substrate and the second layer, wherein the first layer and the second layer are located between at least the front substrate and the front electrode;

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

wherein the first conductive layer comprises silver, which is contacts said third layer comprising zinc oxide and/or zinc aluminum oxide.

6. The photovoltaic device of claim 1, wherein the second conductive layer of the front electrode has a refractive index (n) of at least about 2.2.

7. The photovoltaic device of claim 1, wherein the second conductive layer of the front electrode directly contacts the semiconductor film.

8. The photovoltaic device of claim 1, wherein first conductive layer is a TCO comprising one or more of zinc oxide, zinc aluminum oxide, tin oxide, indium-tin-oxide, indium zinc oxide, tin antimony oxide, and zinc gallium aluminum oxide.

9. The photovoltaic device of claim 1, wherein the first conductive layer comprises silver.

10. The photovoltaic device of claim 1, wherein the semiconductor film comprises (i) a-Si, or (ii) a first layer comprising CdS and a second layer comprising CdTe.

11. The photovoltaic device of claim 1, wherein the photovoltaic device, including the front electrode and front substrate, has an ambient transmission of at least 85% into the semiconductor film in at least a substantial part of the wavelength range of from about 450-600 nm.

12. The photovoltaic device of claim 1, wherein the photovoltaic device, including the front electrode and front substrate, has an ambient transmission of at least 87% into the semiconductor film in at least a substantial part of the wavelength range of from about 450-600 nm.

13. A photovoltaic device comprising:

a front glass substrate;

a front electrode;

a semiconductor film, wherein the front electrode is located between at least the front substrate and the semiconductor film; and

wherein the front electrode of the photovoltaic device comprises a first conductive layer and a second conductive layer, wherein the second conductive layer is located between at least the first conductive layer and the semiconductor film, and wherein the second conductive layer comprises titanium oxide doped niobium.

14. The photovoltaic device of claim 13, wherein the titanium oxide is doped with from about 0.01 to 10% Nb, and may optionally further include aluminum.

15. The photovoltaic device of claim 13, wherein the titanium oxide is doped with from about 0.1 to 5% Nb.

16. The photovoltaic device of claim 13, further comprising:

a first layer comprising one or more of silicon nitride, silicon oxide, silicon oxynitride, and/or tin oxide;

a second layer comprising one or more of titanium oxide and/or niobium oxide, wherein at least the first layer is located between the front substrate and the second layer, wherein the first layer and the second layer are located between at least the front substrate and the front electrode;

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

wherein the first conductive layer comprises silver, which is contacts said third layer comprising zinc oxide and/or zinc aluminum oxide, and wherein said second conductive layer comprising titanium oxide doped niobium is provided between at least the semiconductor film and the first conductive layer comprising silver.

17. The photovoltaic device of claim 13, wherein the second conductive layer comprising titanium oxide doped niobium has a refractive index (n) of at least about 2.2.

18. The photovoltaic device of claim 13, wherein the second conductive layer comprising titanium oxide doped niobium directly contacts the semiconductor film.

19. The photovoltaic device of claim 13, wherein first conductive layer is a TCO comprising one or more of zinc oxide, zinc aluminum oxide, tin oxide, indium-tin-oxide, indium zinc oxide, tin antimony oxide, and zinc gallium aluminum oxide.

20. The photovoltaic device of claim 13, wherein the first conductive layer comprises silver.

21. The photovoltaic device of claim 13, wherein the semiconductor film comprises (i) a-Si, or (ii) a first layer comprising CdS and a second layer comprising CdTe.

22. The photovoltaic device of claim 13, wherein the photovoltaic device, including the front electrode and front substrate, has an ambient transmission of at least 85% into the semiconductor film in at least a substantial part of the wavelength range of from about 450-600 nm.

23. The photovoltaic device of claim 13, wherein the photovoltaic device, including the front electrode and front substrate, has an ambient transmission of at least 87% into the semiconductor film in at least a substantial part of the wavelength range of from about 450-600 nm.