Controllable hydrothermal synthesis of nanocrystal TiO2 particles and their use in dye-sensitized solar cells

Abstract

A simple method for the controllable hydrothermal synthesis of nanocrystalline anatase TiO2 (nc-TiO2) particles involving the selection of suitable organic alkali peptizing agents is reported. A dye-sensitized solar cell (DSSC) with square-like nc-TiO2 particles with side lengths about 8–13 nm—prepared using tetraethylammonium hydroxide (TEAOH)—in the photoelectrode showed higher photovoltaic performance than two other DSSCs with square-like nc-TiO2 particles with side lengths about 7–10 nm—prepared using tetrabutylammonium hydroxide—or elongated nc-TiO2 particles with lengths about 18–35 nm and width about 10–18 nm—prepared using tetramethylammonium hydroxide (TMAOH)—in the photoelectrodes. When a scattering layer prepared from sub-micron size spheres or cone-like nc-TiO2 particles—synthesized using a higher concentration of TMAOH—was added on top of the photoelectrode fabricated from nc-TiO2 synthesized with TEAOH, the energy conversion efficiency of the DSSC was markedly increased from 6.77% to 8.18%.