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Journal of Nanomaterials
Volume 2015, Article ID 579510, 7 pages
http://dx.doi.org/10.1155/2015/579510
Research Article

Cu(In,Ga)Se2 Thin Films Codoped with Sodium and Bismuth Ions for the Use in the Solar Cells

Department of Chemical Engineering, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan

Received 8 October 2014; Revised 31 March 2015; Accepted 9 April 2015

Academic Editor: Edward A. Payzant

Copyright © 2015 Fu-Shan Chen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The codoping effects of sodium and bismuth ions on the characteristics of Cu(In,Ga)Se2 films prepared via the solution process were investigated in this study. When sodium and bismuth ions were incorporated into Cu(In,Ga)Se2, the ratio of the intensity of (112) diffraction peak to that of (220/204) diffraction peak was greatly increased. The codoping process not only enlarged the sizes of the grains in the films but also resulted in densification of the films. The carrier concentration of Cu(In,Ga)Se2 was found to be effectively increased to cause a reduction in the resistivity of the films. The above phenomena were attributed to the densified microstructures of the films and a decrease in the amount of the donor-type defects. The leakage current of the solar cells was found to be also decreased via the codoping process. Owing to the improved electrical properties of Cu(In,Ga)Se2 films, the conversion efficiency of the fabricated solar cells was significantly enhanced.