Author(s)

Motoki Hironaka¹, Taro Toyoda¹, Kanae Hori¹, Yuhei Ogomi², Shuzi Hayase², Qing Sheng^1*

¹Department of Engineering Science, The University of Electro-Communications, Chofu, Japan.
²Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Kitakyushu, Japan.

Recently, semiconductor quantum dot (QD) sensitized solar cells (QDSSCs) are expected to achieve higher conversion efficiency because of the large light absorption coefficient and multiple exciton generation in QDs. The morphology of TiO₂ electrode is one of the most important factors in QDSSCs. Inverse opal (IO) TiO₂ electrode, which has periodic mesoporous structure, is useful for QDSSCs because of better penetration of electrolyte than conventional nanoparticulate TiO₂ electrode. In addition, the ordered three dimensional structure of IO-TiO₂ would be better for electron transport. We have found that open circuit voltage Voc of QDSSCs with IO-TiO₂ electrodes was much higher (0.2 V) than that with nanoparticulate TiO₂ electrodes. But short circuit current density Jsc was lower in the case of IO-TiO2 electrodes because of the smaller surface area of IO-TiO₂. In this study, for increasing surface area of IO-TiO₂, we applied TiCl₄ post treatment on IO-TiO₂ and investigated the effect of the post treatment on photovoltaic properties of CdSe QD sensitized IO-TiO₂ solar cells. It was found that J_sc could be enhanced due to TiCl₄ post treatment, but decreased again for more than one cycle treatment, which indicates excess post treatment may lead to worse penetration of electrolyte. Our results indicate that the appropriate post treatment can improve the energy conversion efficiency of the QDSSCs.

Quantum Dot Sensitized Solar Cells, Inverse Opal Structure, TiCl₄ Post Treatment, Morphology of the TiO₂ Electrode

Hironaka, M. , Toyoda, T. , Hori, K. , Ogomi, Y. , Hayase, S. and Sheng, Q. (2017) Photovoltaic Properties of CdSe Quantum Dot Sensitized Inverse Opal TiO₂ Solar Cells: The Effect of TiCl₄ Post Treatment. Journal of Modern Physics, 8, 522-530. doi: 10.4236/jmp.2017.84034.