Fabrication of Ion-Paths for Ionic Liquid Type Quasi-Solid Dye Sensitized Solar Cell
- PDF / 4,613,360 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 22 Downloads / 147 Views
0965-S06-39
Fabrication of Ion-Paths for Ionic Liquid Type Quasi-Solid Dye Sensitized Solar Cell Takashi Kado1, Takehito Kato1, Takeshi kogo1, Fumi Inakazu1, Yusuke Noma1, Yuhei Ogomi1, Yoshihiro Yamaguchi2, Mitsuru Kohno2, and Shuzi Hayase1 1 Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino Wakamatsu-ku, Kitakyushu, 808-0196, Japan 2 Shin-nippon Steel Chemical Co. Ltd., Kitakyushu, 804-8503, Japan ABSTRACT A direction to increasing photovoltaic performances of dye sensitized solar cells (DSC) is proposed. An interface between TiO2/dye and an electrolyte layer is focused on. It is proved that better coverage of TiO2 layers with dye molecules increases photovoltaic performances, where dye staining is carried out in pressurized CO2 atmosphere. This is explained by decreases in the amount of surface traps on TiO2 nano-particles, which is discussed by thermally stimulated current (TSC). The decrease in the surface trap density increases electron diffusion coefficient and improves electron lifetime in TiO2 layers. In addition, the TiO2-staining with dye molecules having the larger dipole moment seems to leave less amount of electron trap. Another crucial research item is solidification. Quasi-solidification is carried out by using surface modified anodically-oxidized Al2O3 films filled with ionic liquids, where ion paths are fabricated on the surface-modified Al2O3 walls by concentrating iodine and iodide molecules on the walls. Because of the fabrication of the ion path, photovoltaic performances increased even after solidification. Grötthuss type mechanism is introduced to explain the increase in the photovoltaic performances after the solidification.
INTRODUCTION Dye sensitized solar cells (DSC) are expected to be one of the future solar cells, because the procedure of the cell preparation are composed of simple coating and heating processes [1]. These simple processes are completely different from conventional Si based solar cells requiring vacuum processes. Because of this, DSCs have a potential to provide low cost solar cells. The efficiencies reached 10-11 % which is much higher than those for other solar cells consisting of organic molecules [2-3]. However, increases in the efficiency are still needed in order to catch up the preceding Si based solar cells [5]. Solidification of liquid electrolytes is the other item to be solved. In this report, the focus is put on TiO2/dye/electrolyte interfaces. Our purpose is to propose a model of what the interface should be.
WORKIN PRINCIPLE The mechanism is summarized in Figure 1 [6]. Dye molecules are photoexcited (a) and electrons are injected into TiO2 layers (b). These electrons diffuse in TiO2 layers (c) and are collected in F/SnO2 layers (d). On the counter electrode, I2 (I3-) molecules are reduces to I-, which is catalyzed with Pt (e). Idiffuses in organic solvents (f) to give electrons to the oxidized dye molecules (g). I- is oxidized to I2 (I3-)
De (d)
Dion
(c) (b)
I2 (h) (a)
(i)
∆V
I2
(e)
e
(f)
I-
Data Loading...
