Diffusion Length in Nanoporous Photoelectrodes of Dye-Sensitized Solar Cells under Operating Conditions Measured by Photocurrent Microscopy.
We determined the carrier diffusion lengths in nanoporous layers of dye-sensitized solar cells by using scanning photocurrent microscopy. The diffusion lengths were found to be 60-100 μm for the conventional cells. In addition, we found a correlation between the carrier diffusion lengths and the cell efficiency, which proved that improvement in the diffusion length is one of the crucial factors for optimizing device performance. The diffusion length was measured for various operating conditions by varying parameters such as solar light intensity and applied electrical voltage. In particular, we observed electric-field-driven, carrier transport phenomena (i.e., drift current) in modified cells. Fitting with the drift-diffusion model enabled us to extract the electric field strengths present in the TiO2 nanoporous layer.
Department of Physics and Division of Energy Systems Research, Ajou University, Suwon 443-749, Korea.
Jae-Ku
JK
Park
Department of Physics and Division of Energy Systems Research, Ajou University, Suwon 443-749, Korea.
Ji-Chul
JC
Kang
Department of Physics and Division of Energy Systems Research, Ajou University, Suwon 443-749, Korea.
Sang Yong
SY
Kim
Department of Physics and Division of Energy Systems Research, Ajou University, Suwon 443-749, Korea.
B H
BH
Son
Department of Physics and Division of Energy Systems Research, Ajou University, Suwon 443-749, Korea.
Ji-Yong
JY
Park
Department of Physics and Division of Energy Systems Research, Ajou University, Suwon 443-749, Korea.
Soonil
S
Lee
Department of Physics and Division of Energy Systems Research, Ajou University, Suwon 443-749, Korea.
Y H
YH
Ahn
diffusion length; dye-sensitized solar cells; nanoporous layers; photocurrent microscopy