Poriferous microtablet of anatase TiO2 growth on an ITO surface for high-efficiency dye-sensitized solar cells

A liquid-phase deposition method enables the synthesis of a unique anatase TiO2 structure, which consists of poriferous microtablets with a hairy nanowire skin and a body constructed by a brick-like assembly of nanocuboids, directly onto an ITO substrate. The poriferous TiO2 microtablets (PTM) have square-shaped, rounded vertices, edges that are 10 µm in length and a thickness of approximately 5 μm. They can be grown at a high density onto an ITO surface from a growth solution that contains ammonium hexafluoro titanate and boric acid. The nanowires that decorate the PTM surface have a diameter of 10 nm and a length of approximately 200 nm. Its bulk structure is constructed from a brick-like assembly of nanocuboids with a width, length and thickness of approximately 10, 20 and 5 nm, respectively. The driving factor for the formation of this structure is oriented attachment under kinetic control. The preliminary results of the application of this structure in dye-sensitized solar cell (DSSC) devices indicate a power conversion efficiency as high as 3.0%. Because the active surface area in the PTM is large enough for dye adsorption (for a typical dye loading as high as approximately 936 nmol/cm2) and surface reactions, a high-efficiency DSSC device may be achievable using this new structure if the optimum conditions are obtained.