Enhanced photon collection of high surface area carbonate-doped mesoporous TiO2 nanospheres in dye sensitized solar cells

Carbonate-doped mesoporous TiO2 nanospheres with anatase phase were successfully synthesized by the simple solvothermal method. The synthesized nanospheres were monodispersed and composed of particles having the size of 10-15 nm. Scanning transmission electron microscopy (STEM) analysis showed nanosphere with large number particles. STEM-mapping clearly showed that Ti, O, and C were homogeneously distributed. Incorporation of carbonate in TiO2 was confirmed by XPS analysis. The peak at 284.3 eV was assigned to C-O and indicated the formation Ti-O-C structure due to carbonate doping in TiO2 lattice. Dye-sensitized solar cells (DSSCs) containing the nanospheres were fabricated by spray coating technique using N719 dye. Carbonate doped mesoporous TiO2 showed enhanced DSSC efficiency (5.4%) compared to undoped (3.4%) and commercially available TiO2 (P25) (2.4%). It indicated (1) higher surface area and incident photon conversion efficiency, (2) lower resistance and longer life time compared with undoped TiO2.