NEW SOLID MEDIUM FOR ELECTROCHEMISTRY AND ITS APPLICATION TO DYE-SENSITIZED SOLAR CELLS - Energy Research Developments: Tidal Energy, Energy Efficiency and Solar Energy - page 107

Chapter 4
N EW S OLID M EDIUM FOR E LECTROCHEMISTRY
AND ITS A PPLICATION TO D YE -S ENSITIZED
S OLAR C ELLS
Masao Kaneko
Faculty of Science, Ibaraki University; 2-1-1 Bunkyo,
Mito, 310-8512 Japan
Abstract
A tight and elastic polysaccharide solid containing excess water was proposed as a solid
medium for electrochemistry. Conventional electrochemical measurements could be
performed in this solid the same as in liquid water. Diffusion coefficients (D app ) of small
molecules and ions in this solid were almost the same as in a liquid. Charge transfer resistance
(R ct ) as well as double layer capacitance (C dl ) at the interface of the electrode/polysaccharide
solid was similar as that of electrode/water interface. Ionic conductivity in this solid was the
same as in liquid water. It was found that bulk convection does not take place in this solid,
which allows discrimination of molecular diffusion from bulk convection. This solid was
successfully applied to solidify the redox electrolyte solution of a dye-sensitized solar cell
giving almost similar light-to-current conversion efficiency as that of a liquid type cell.
Introduction
It has well been known that hydrophilic polymers form a hydrogel that contains excess
water inside [1]. Such hydrogels have been used for water adsorbent, electrophoresis,
immobilizing enzymes and medicines, etc. However, diffusion of molecules and ions in these
gels has scarcely been studied due to the lack of suitable methodology. The present author has
found that a tight and elastic polysaccharide solid containing excess water can be used as a
solid medium for electrochemical measurements the same as liquid water, and that diffusion
of molecules and ions takes place in this solid the same as in a liquid [2-6]. This allows the
solid to be used not only as a medium for electrochemistry, but also as a solid reactor for
various chemical reactions. It is of further interest that in this solid bulk convection does not