High Efficiency Dye-Sensitized Solar Cells by Metal-Free Organic Dye and Perpendicular ZnO Nanosheet Thick Film

  • Dr Eiji Hosono, Nano-Energy Materials Group, Energy Technology Research Institute, National Institute of Advanced Industrial Science and Techno, Japan
  • Mr Yosuke Mitsui, Tokyo University of Science, Japan
  • Dr Haoshen Zhou, Nano-Energy Materials Group, Energy Technology Research Institute, National Institute of Advanced Industrial Science and Techno, Japan

    • ZnO has attracted attention as a fascinating alternative to TiO2 in DSC because ZnO and TiO2 exhibit the similar level of the lowest conduction band and electron injection process from excited dyes in DSC. Moreover, the carrier lifetime in ZnO is significantly longer. However, the studies of high efficiency DSC using ZnO with exception of basic study have been very few because the conversion efficiency of around 2 % is much lower than that using TiO2.
    Recently we reported the high efficiency DSC of around 4%[1] using ZnO and N-719 dyes. The nanostructure control of the ZnO electrode was very critical in order to obtain the high efficiency solar cells.
    Moreover, in the development of DSC, the works of metal-free dyes are important in addition to the study of high efficiency solar cells. The general dyes for high efficiency cells are Ru complex dyes such as N3 and N-719. The ruthenium metal, which is rare metal, is high cost and a few in the earth.
    In this work, we repot the high efficient DSC using metal-free organic dyes (D149) and nanostructured ZnO electrodes. The efficiency of 4.27% is larger than that of around 4% by the DSC using ZnO and N-719. The result, which indicates that the efficiency of DSC using organic dyes is larger than that using ruthenium dyes, is very important for the study of DSC.

    References
    [1] E. Hosono, et al., Adv. Mater., 17, 209 (2005). J. Photochem. Photobiol. A: Chem., 179, 81 (2006).