Porous “sponge-like” anatase TiO2 via polymer templates: synthesis, characterization, and performance as a light-scattering material

The synthesis of porous “sponge-like” TiO 2 via a polymer gel coating technique is presented. The experimental procedure involves the preparation of a gelled polymerizable microemulsion. The polymerization of the latter leads to porous poly- N -isopropylacrylamide which forms a hydrogel in the presence of water. Via solvent exchange, a suitable TiO 2 precursor is infiltrated into this structure after which its in situ hydrolysis is triggered to form porous amorphous TiO 2 . The subsequent calcination step allows the removal of the polymer template and the transformation of amorphous TiO 2 into porous, crystalline anatase with domain sizes ranging from 200 to 250 nm. As a means of verification and proof of concept, this material is tested as light-scattering layer in dye-sensitized solar cells (DSSC), and it is found that the resulting solar cell performance is comparable to commercially available TiO 2 . However, an increased tendency to form rutile during DSSC fabrication was noticed when compared to commercial TiO 2 . As there is a large potential for optimizing the synthesis, the proposed procedure is a promising route towards porous TiO 2 that performs significantly better as scattering layer in light-harvesting and optical devices.