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

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?C13 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?C10 nm??prepared using tetrabutylammonium hydroxide??or elongated nc-TiO₂ particles with lengths about 18?C35 nm and width about 10?C18 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%.