Photovoltaic Element, Photovoltaic Module Comprising Photovoltaic Element, and Method of Fabricating Photovoltaic Element

Abstract

A photovoltaic element comprising a transparent conductive film capable of improving weather resistance is obtained. This photovoltaic element includes a photoelectric conversion layer, and a transparent conductive film formed on a surface of the photoelectric conversion layer and including an indium oxide layer having (222) orientation and two X-ray diffraction peaks, in which the two X-ray diffraction peaks of the indium oxide layer is constituted by a first peak on a low angle side and a second peak on a high angle side having a peak intensity level lower than the first peak.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a structure of a photovoltaic module comprising a photovoltaic element according to an embodiment of the present invention;

FIG. 2 is a diagram for illustrating the relation between pressures of a gas mixture of Ar and O₂ and X-ray diffraction spectra of transparent conductive films;

FIG. 3 is a diagram for illustrating the relation between pressures of a gas mixture of Ar and O₂ and normalized cell outputs (Pmax) of photovoltaic elements;

FIG. 4 is a diagram for illustrating the relation between pressures of a gas mixture of Ar and O₂, the contents of WO₃ in In₂O₃ targets, and intensity ratios (P1/P2) between first peaks (P1) and second peaks (P2) of the transparent conductive films;

FIG. 5 is a diagram illustrating the relation between intensity ratios (P1/P2) of first peaks (P1) and second peaks (P2) of transparent conductive films and normalized weather resistance of photovoltaic elements.

FIG. 6 is a diagram for illustrating the relation between pressures of a mixed gas of Ar and O₂, the contents of WO₃ in In₂O₃ targets, and normalized cell outputs (Pmax) of photovoltaic elements.

Claims

1. A photovoltaic element comprising: a photoelectric conversion layer; anda transparent conductive film formed on a surface of said photoelectric conversion layer and including an indium oxide layer having (222) orientation and two X-ray diffraction peaks, whereinsaid two X-ray diffraction peaks of said indium oxide layer are constituted by a first peak on a low angle side and a second peak on a high angle side having a peak intensity level lower than said first peak.

2. The photovoltaic element according to claim 1, wherein said first peak on said low angle side of said indium oxide layer has an angle 2θ (θ:X-ray diffraction angle) in the vicinity of 30.1 degrees, andsaid second peak on said high angle side of said indium oxide layer has an angle 2θ (θ: X-ray diffraction angle) in the vicinity of 30.6 degrees.

3. The photovoltaic element according to claim 1, wherein the intensity ratio between said first peak and said second peak of said indium oxide layer is at least 1.

4. The photovoltaic element according to claim 3, wherein, the intensity ratio between said first peak and said second peak of said indium oxide layer is at most 2.

5. The photovoltaic element according to claim 1, wherein said indium oxide layer includes W.

6. The photovoltaic element according to claim 1, wherein said indium oxide layer includes Sn.

7. The photovoltaic element according to claim 1, further comprising: a semiconductor layer formed thereon with said transparent conductive film and consisting of at least either an amorphous semiconductor or a microcrystalline semiconductor; anda collector formed on said transparent conductive film.

8. The photovoltaic element according to claim 7, wherein said semiconductor layer includes an amorphous silicon layer.

9. A photovoltaic module comprising: a photoelectric conversion layer;a plurality of photovoltaic elements, each of which including a transparent conductive film formed on a surface of said photoelectric conversion layer and including an indium oxide layer having (222) orientation and two X-ray diffraction peaks;a transparent surface protector arranged on surfaces of said transparent conductive films of said plurality of photovoltaic elements; anda resin film so arranged as to hold said plurality of photovoltaic elements between said surface protector and said resin film, whereinsaid two X-ray diffraction peaks of said indium oxide layer of said photovoltaic element are constituted by a first peak on a low angle side and a second peak on a high angle side having a peak intensity level lower than said first peak.

10. The photovoltaic module according to claim 9, wherein said first peak on said low angle side of said indium oxide layer has an angle 2θ (θ: X-ray diffraction angle) in the vicinity of 30.1 degrees, andsaid second peak on said high angle side of said indium oxide layer has an angle 2θ (0 X-ray diffraction angle) in the vicinity of 30.6 degrees.

11. The photovoltaic module according to claim 9, wherein the intensity ratio between said first peak and said second peak of said indium oxide layer is at least 1.

12. The photovoltaic module according to claim 11, wherein the intensity ratio between said first peak and said second peak of said indium oxide layer is at most 2.

13. The photovoltaic module according to claim 9, wherein said indium oxide layer includes W.

14. The photovoltaic module according to claim 9, wherein said indium oxide layer includes Sn.

15. The photovoltaic module according to claim 9, further comprising: a semiconductor layer formed thereon with said transparent conductive film and consisting of at least either an amorphous semiconductor or a microcrystalline semiconductor; anda collector formed on said transparent conductive film.

16. The photovoltaic module according to claim 9, wherein said semiconductor layer includes an amorphous silicon layer.

17. A method of fabricating a photovoltaic element, comprising steps of: forming a photoelectric conversion layer; andforming a transparent conductive film including an indium oxide layer having (222) orientation and two X-ray diffraction peaks on a surface of said photoelectric conversion layer by ion plating, whereinsaid two X-ray diffraction peaks of said indium oxide layer are constituted by a first peak on a low angle side and a second peak on a high angle side having a peak intensity level lower than said first peak.

18. The method of fabricating a photovoltaic element according to claim 17, wherein said step of forming said transparent conductive film includes a step of forming said transparent conductive film by ion plating under a condition of an ion energy of at least 10 eV and not more than 20 eV.

19. The method of fabricating a photovoltaic element according to claim 17, wherein said step of forming said transparent conductive film includes a step of forming said transparent conductive film by ion plating under a condition where the content of WO3 powder in a target is at least 1 percent by weight and not more than 3 percent by weight and a pressure of a gas mixture of Ar and O2 is at least 0.7 Pa and not more than 1.0 Pa.

20. The method of fabricating a photovoltaic element according to claim 17, wherein said step of forming said transparent conductive film includes a step of forming said transparent conductive film prepared from a target containing SnO2 powder by ion plating under a condition where a pressure of a gas mixture of Ar and O2 is at least 0.4 Pa and not more than 1.0 Pa.