Photovoltaic device and process for producing same

• US 20080196761A1
• Filed: 12/21/2007
• Published: 08/21/2008
• Est. Priority Date: 02/16/2007
• Status: Abandoned Application

• Current Assignee: Mitsubishi Heavy Industries, Ltd.
• Original Assignee: Mitsubishi Heavy Industries, Ltd.
• Inventors: Yamaguchi, Kengo, Yamauchi, Yasuhiro, Nakano, Youji, Takeuchi, Yoshiaki
• Application Number:
  US12/003,261
• Publication Number:
  US 20080196761A1
• Time in Patent Office: Days
• US Class Current: 136/258
• CPC Class Codes: H01L 31/0236 Special surface textures
• CPC Class Codes: H01L 31/056 the light-reflecting means being of the back surface reflector [BSR] type
• CPC Class Codes: H01L 31/076 Multiple junction or tandem solar cells
• CPC Class Codes: H01L 31/077 the devices comprising monocrystalline or polycrystalline materials
• CPC Class Codes: H01L 31/182 Special manufacturing methods for polycrystalline Si, e.g. Si ribbon, poly Si ingots, thin films of polycrystalline Si
• CPC Class Codes: H01L 31/1884 Manufacture of transparent electrodes, e.g. TCO, ITO
• CPC Class Codes: Y02E 10/52 PV systems with concentrators
• CPC Class Codes: Y02E 10/546 Polycrystalline silicon PV cells
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A photovoltaic device and a process for producing the photovoltaic device that combine a high photovoltaic conversion efficiency with a high level of productivity. The photovoltaic device includes at least a transparent electrode-bearing substrate, prepared by providing a transparent electrode layer on a transparent, electrically insulating substrate, and a photovoltaic layer containing mainly crystalline silicon-based semiconductors and a back electrode layer formed sequentially on the transparent electrode layer of the transparent electrode-bearing substrate, wherein the surface of the transparent electrode layer of the transparent electrode-bearing substrate has a shape that contains a mixture of coarse and fine roughness, and exhibits a spectral haze ratio of 20% or greater for wavelengths of from 550 nm to 800 nm, and the photovoltaic layer containing mainly crystalline silicon-based semiconductors has a film thickness of from 1.2 μm to 2 μm, and a Raman ratio of from 3.0 to 8.0.

Claims

1. A photovoltaic device comprising at least a transparent electrode-bearing substrate, prepared by providing a transparent electrode layer on a transparent, electrically insulating substrate, and a photovoltaic layer comprising mainly crystalline silicon-based semiconductors and a back electrode layer formed sequentially on the transparent electrode layer of the transparent electrode-bearing substrate, wherein

the transparent electrode-bearing substrate has a surface shape comprising a mixture of coarse and fine roughness, and exhibits a spectral haze ratio of 20% or greater for wavelengths of not less than 550 nm and not more than 800 nm, and

the photovoltaic layer comprising mainly crystalline silicon-based semiconductors has a film thickness of not less than 1.2 μ

m and not more than 2 μ

m, and a Raman ratio of not less than 3.0 and not more than 8.0.

2. The photovoltaic device according to claim 1, further comprising a photovoltaic layer comprising mainly amorphous silicon-based semiconductors between the transparent electrode-bearing substrate and the photovoltaic layer comprising mainly crystalline silicon-based semiconductors.

3. The photovoltaic device according to claim 2, further comprising an intermediate contact layer between the photovoltaic layer comprising mainly amorphous silicon-based semiconductors and the photovoltaic layer comprising mainly crystalline silicon-based semiconductors.

4. The photovoltaic device according to claim 1, wherein a surface of the transparent electrode of the transparent electrode-bearing substrate comprises a plurality of ridges and a plurality of flat portions, surfaces of the ridges and flat portions comprise a multitude of continuous micro-protrusions,

a height of the ridges in a direction perpendicular to the substrate surface is not less than 0.4 μ

m and not more than 0.7 μ

m,

a number of ridges within a 10 μ

m square area of the substrate surface is not less than 15 and not more than 50,

base diameter of the multitude of micro-protrusions is not less than 0.1 μ

m and not more than 0.3 μ

m, and a ratio of height/base diameter for the micro-protrusions is not less than 0.7 and not more than 1.2.

14. The photovoltaic device according to claim 2, wherein

during formation of the photovoltaic layer comprising mainly amorphous silicon-based semiconductors, a p-layer, an i-layer and an n-layer are formed sequentially, and

the n-layer of the photovoltaic layer comprising mainly amorphous silicon-based semiconductors is formed from a layer comprising mainly amorphous silicon-based semiconductors, and a layer comprising mainly crystalline silicon-based semiconductors.

16. The photovoltaic device according to claim 2, wherein a buffer layer is provided between the p-layer and the i-layer of the photovoltaic layer comprising mainly amorphous silicon-based semiconductors.

5. A process for producing a photovoltaic device comprising:

preparing a transparent electrode-bearing substrate by forming a transparent electrode layer on a transparent, electrically insulating substrate; and

sequentially forming at least a photovoltaic layer comprising mainly amorphous silicon-based semiconductors and a back electrode layer on the transparent electrode layer of the transparent electrode-bearing substrate, wherein

the transparent electrode-bearing substrate has a surface shape comprising a mixture of coarse and fine roughness, and exhibits a spectral haze ratio of 20% or greater for wavelengths of not less than 550 nm and not more than 800 nm, and

a hetero-phase-blocking layer that blocks hetero-phases from penetrating through the photovoltaic layer comprising mainly amorphous silicon-based semiconductors from a surface on the transparent electrode layer side to a surface on the back electrode layer side is formed within the photovoltaic layer.

6. The process for producing a photovoltaic device according to claim 5, wherein during formation of the photovoltaic layer comprising mainly amorphous silicon-based semiconductors, a p-layer, an i-layer and an n-layer are formed sequentially, and

the hetero-phase-blocking layer is formed during formation of the i-layer, by forming a portion of the i-layer at a slower rate than other portions of the i-layer.

7. The process for producing a photovoltaic device according to claim 5, wherein during formation of the photovoltaic layer comprising mainly amorphous silicon-based semiconductors, a p-layer, an i-layer and an n-layer are formed sequentially, and

the hetero-phase-blocking layer is formed during formation of the n-layer, by forming an amorphous layer within at least a portion of the n-layer.

8. The process for producing a photovoltaic device according to claim 5, wherein during formation of the photovoltaic layer comprising mainly amorphous silicon-based semiconductors, a p-layer, an i-layer and an n-layer are formed sequentially, and

the hetero-phase-blocking layer is formed during formation of the n-layer, by forming at least a portion of the n-layer under pressure of not less than 200 Pa.

12. The process for producing a photovoltaic device according to claim 5, wherein a photovoltaic layer comprising mainly crystalline silicon-based semiconductors is formed between the photovoltaic layer comprising mainly amorphous silicon-based semiconductors and the back electrode.

9. A process for producing a photovoltaic device comprising:

preparing a transparent electrode-bearing substrate by forming a transparent electrode layer on a transparent, electrically insulating substrate; and

sequentially forming at least a photovoltaic layer comprising mainly amorphous silicon-based semiconductors and a back electrode layer on the transparent electrode layer of the transparent electrode-bearing substrate, wherein

the transparent electrode-bearing substrate has a surface shape comprising a mixture of coarse and fine roughness, and exhibits a spectral haze ratio of 20% or greater for wavelengths of not less than 550 nm and not more than 800 nm, and

a hetero-phase prevention layer that prevents the formation of hetero-phases that penetrate through the photovoltaic layer from the surface on the transparent electrode layer side to the surface on the back electrode layer side is formed between formation of the transparent electrode layer and formation of the photovoltaic layer.

10. The process for producing a photovoltaic device according to claim 9, wherein the hetero-phase prevention layer is formed by smoothing the protrusions of the transparent electrode layer.

11. The process for producing a photovoltaic device according to claim 9, wherein the hetero-phase prevention layer is formed by subjecting the transparent electrode layer surface to an ion treatment.

13. A photovoltaic device comprising at least a transparent electrode-bearing substrate, prepared by providing a transparent electrode layer on a transparent, electrically insulating substrate, and a photovoltaic layer comprising mainly amorphous silicon-based semiconductors and a back electrode layer formed sequentially on the transparent electrode layer of the transparent electrode-bearing substrate, wherein

the transparent electrode-bearing substrate has a surface shape comprising a mixture of coarse and fine roughness, and exhibits a spectral haze ratio of 20% or greater for wavelengths of not less than 550 nm and not more than 800 nm, and

a hetero-phase-blocking layer that blocks hetero-phases from penetrating through the photovoltaic layer comprising mainly amorphous silicon-based semiconductors from a surface on the transparent electrode layer side to a surface on the back electrode layer side is provided within the photovoltaic layer.

15. The photovoltaic device according to claim 13, wherein

during formation of the photovoltaic layer comprising mainly amorphous silicon-based semiconductors, a p-layer, an i-layer and an n-layer are formed sequentially, and

the n-layer of the photovoltaic layer comprising mainly amorphous silicon-based semiconductors is formed from a layer comprising mainly amorphous silicon-based semiconductors, and a layer comprising mainly crystalline silicon-based semiconductors.

17. The photovoltaic device according to claim 13, wherein a buffer layer is provided between the p-layer and the i-layer of the photovoltaic layer comprising mainly amorphous silicon-based semiconductors.

18. The photovoltaic device according to claim 13, further comprising a photovoltaic layer comprising mainly crystalline silicon-based semiconductors between the photovoltaic layer comprising mainly amorphous silicon-based semiconductors and the back electrode layer.

19. The photovoltaic device according to claim 18, wherein the photovoltaic layer comprising mainly crystalline silicon-based semiconductors has a film thickness of not less than 1.2 μ

m and not more than 2 μ

m, and a Raman ratio of not less than 3.0 and not more than 8.0.

20. The photovoltaic device according to claim 13, further comprising a photovoltaic layer, which comprises mainly a crystalline silicon-based semiconductor, and a crystalline or amorphous silicon-germanium-based semiconductor, between the photovoltaic layer comprising mainly amorphous silicon-based semiconductors and the back electrode layer.

21. The photovoltaic device according to claim 13, further comprising a photovoltaic layer, which comprises mainly a crystalline or amorphous silicon-based semiconductor, and a crystalline or amorphous silicon-germanium-based semiconductor, between the photovoltaic layer comprising mainly amorphous silicon-based semiconductors and the back electrode layer.