CubicTiO2as a potential light absorber in solar-energy conversion

Materials are currently sought for use in the photo-induced decomposition of water on crystalline electrodes. Titanium dioxide is valuable in this respect. The electronic structural properties of cubic ${\mathrm{TiO}}_2$ polymorphs were investigated by means of first-principles methods. We demonstrate that both fluorite- and pyrite-type ${\mathrm{TiO}}_2$ have important optical absorptive transitions in the region of the visible light. A cubic ${\mathrm{TiO}}_2$ phase that can efficiently absorb the sunlight would be an important candidate material for the development of the solar cells. Also, we present results on the $\mathrm{Ti}$ $L$ edges for the two different titania forms. We predict that a qualitative spectroscopic discrimination of the cubic polymorphs can be achieved by following the $\mathrm{Ti}$ $2p\to 3d$ x-ray transitions.