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Journal of Nanomaterials
Volume 2016, Article ID 7403019, 10 pages
http://dx.doi.org/10.1155/2016/7403019
Research Article

Surface Modification of Porous Photoelectrode Using Etching Process for Efficiency Enhancement of ZnO Dye-Sensitized Solar Cells

1Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand
2Thailand Center of Excellence in Physics (ThEP Center), CHE, Bangkok 10400, Thailand

Received 24 May 2016; Accepted 26 June 2016

Academic Editor: Meiyong Liao

Copyright © 2016 Sutthipoj Sutthana 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

Surface modification of porous ZnO photoelectrode using one- and two-step etching process is investigated for enhancing power conversion efficiency of ZnO dye-sensitized solar cells. ZnO films are modified by the diluted NH4OH solutions for one-step etching process and used as photoelectrode of dye-sensitized solar cells. Rough porous films are observed after one-step etching process. The fabricated cells based on the optimized one-step etched films show a significant increase in short-circuit current density. The short-circuit current density is directly changed with amount of dye adsorption, which is related to specific surface area. The etched films exhibit higher specific surface area over two times than nonetched films. Thus, the large specific surface area is the key success for increasing amount of dye adsorption. Internal electrochemical property of fabricated cells is also improved, indicating that chemical surface of ZnO films is modified in the same time. The DSSCs fabricated on two-step etched films with NH4OH and mixed acid HCl : HNO3 show the maximum power conversion efficiency of 2.26%. Moreover, fill factor is also increased due to better redox process because of the formation of fine porous structure during the etching process. Therefore, these results implied that the roles of etching processes are improving specific surface area and fine porous formation which can provide better dye adsorption and redox process for dye-sensitized solar cell application.