Inverse opal photoelectrode of Nb-doped TiO 2 nanoparticles for dye-sensitized solar cell

In this study, Nb-doped TiO 2 nanoparticles were prepared by solution synthesis, and utilized as photoelectrode for dye-sensitized solar cell aiming to obtain better photon-to-current conversion efficiency. Nb doping was carried out using two different Nb precursors, and subsequent hydrothermal treatment resulted in the size-controlled (~10 nm) Nb-doped TiO 2 nanoparticles with typical ellipsoidal shapes and anatase morphologies. It was observed that NbCl 2 precursor resulted in more uniform particle size, while Nb oxalate resulted in relatively broader particle size distributions and higher aspect ratio ellipsoid. Using these nanoparticles, 10 μm-thick porous inverse opal (IO) photoelectrodes were fabricated by coating the mixed aqueous dispersions of Nb-TiO 2 nanoparticles and polystyrene particles of 270 nm diameter on conductive glass followed by thermal sintering. DSSC single cell performance tests revealed that a photoelectrode from 2 mol% Nb- TiO 2 obtained from NbCl 2 exhibited 20 % enhancement for solar cell efficiency compared to bare TiO 2 IO.