Photovoltaic element, photovoltaic module comprising photovoltaic element, and method of fabricating photovoltaic element

Abstract

A photovoltaic element capable of improving weather resistance is obtained. This photovoltaic element includes a photoelectric conversion layer, a first transparent conductive film formed on a surface of the photoelectric conversion layer closer to an incidence side and including a first indium oxide layer having (222) orientation and two X-ray diffraction peaks, and a second transparent conductive film formed on a surface of the photoelectric conversion layer opposite to the incidence side and including a second indium oxide layer having (222) orientation and one X-ray diffraction peak.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a structure of a photovoltaic module comprising photovoltaic elements 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 in forming first transparent conductive films closer to incidence sides respectively and X-ray diffraction spectra of the first transparent conductive films;

FIG. 3 is a diagram for illustrating the relation between pressures of a gas mixture of Ar and O₂ in forming first transparent conductive films closer to incidence sides respectively 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 in forming first transparent conductive films closer to incidence sides respectively, the contents of WO₃ in targets, and intensity ratios (P1/P2) between first peaks (P1) and second peaks (P2) of the transparent conductive films;

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

FIG. 6 is a diagram for illustrating the relation between pressures of a gas mixture of Ar and O₂ in forming first transparent conductive films closer to incidence sides respectively, the contents of WO 3 in targets, and normalized cell outputs (Pmax) of photovoltaic elements; and

FIG. 7 is a diagram for illustrating the relation between pressures of a gas mixture of Ar and O₂ in forming second transparent conductive films on opposite sides to incidence sides respectively, and normalized weather resistance of photovoltaic elements.

Claims

1. A photovoltaic element comprising: a photoelectric conversion layer;a first transparent conductive film formed on a surface of said photoelectric conversion layer closer to an incidence side and including a first indium oxide layer having (222) orientation and two X-ray diffraction peaks; anda second transparent conductive film formed on a surface of said photoelectric conversion layer opposite to said incidence side and including a second indium oxide layer having (222) orientation and one X-ray diffraction peak.

2. The photovoltaic element according to claim 1, wherein said X-ray diffraction peak of said second 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 said two X-ray diffraction peaks of said first indium oxide layer are constituted by a first peak on a low angle side having an angle 2θ (θ: X-ray diffraction angle) in the vicinity of 30.1 degrees, and a second peak on a high angle side with a peak intensity level lower than said first peak, having an angle 2θ (θ: X-ray diffraction angle) in the vicinity of 30.6 degrees.

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

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

6. The photovoltaic element according to claim 1, wherein said first indium oxide layer and said second indium oxide layer include W.

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

8. The photovoltaic element according to claim 1, wherein said first indium oxide layer and said second indium oxide layer include Sn.

9. A photovoltaic module comprising: a photoelectric conversion layer;a plurality of photovoltaic elements, each of which including a first transparent conductive film formed on a surface of said photoelectric conversion layer closer to an incidence side and including a first indium oxide layer having (222) orientation and two X-ray diffraction peaks, and a second transparent conductive film formed on a surface of said photoelectric conversion layer opposite to said incidence side and including a second indium oxide layer having (222) orientation and one X-ray diffraction peak;a transparent surface protector arranged on a surface of said first transparent conductive film closer to said incidence side; anda resin film arranged on a surface of said second transparent conductive film opposite to the incidence side.

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

11. The photovoltaic module according to claim 9, wherein said two X-ray diffraction peaks of said first indium oxide layer are constituted by a first peak on a low angle side having an angle 2θ (θ: X-ray diffraction angle) in the vicinity of 30.1 degrees and a second peak on a high angle side with a peak intensity level lower than said first peak, having an angle 2θ (θ: X-ray diffraction angle) in the vicinity of 30.6 degrees.

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

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

14. The photovoltaic module according to claim 9, wherein said first indium oxide layer and said second indium oxide layer include W.

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

16. The photovoltaic module according to claim 9, wherein said first indium oxide layer and said second indium oxide layer include Sn.

17. A method of fabricating a photovoltaic element, comprising steps of: forming a photoelectric conversion layer;forming a first transparent conductive film including a first indium oxide layer having (222) orientation and two X-ray diffraction peaks on a surface of said photoelectric conversion layer closer to an incidence side by ion plating; andforming a second transparent conductive film including a second indium oxide layer having (222) orientation and one X-ray diffraction peak on a surface of said photoelectric conversion layer opposite to the incidence side by ion plating.

18. The method of fabricating a photovoltaic element according to claim 17, wherein said step of forming said first transparent conductive film includes a step of forming said first transparent conductive film by ion plating under a condition of an ion energy of at least 10 eV and not more than 20 eV, andsaid step of forming said second transparent conductive film includes a step of forming said second 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 first transparent conductive film includes a step of forming said first transparent conductive film by ion plating under a condition where the content of WO3 powder in a target consisting of indium oxide (In2O3) 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 first transparent conductive film includes a step of forming said first transparent conductive film prepared from a target consisting of indium oxide (In2O3) 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.