Tuning of the flat-band potentials of nanocrystalline TiO 2 and SnO 2 particles with an outer-shell MgO layer

Abstract

Flat-Band (FB) potentials of TiO 2 and SnO 2 nanoparticles shifted negatively once they were coated with a thin insulating MgO layer. For core-shell structured TiO 2–MgO and SnO 2–MgO composites, incorporation of 1% (w/w) of MgO results in negative shift in FB potential of TiO 2 and SnO 2 nanoparticles by − 0.15 eV and − 0.38 eV, respectively. The negative shift of FB increased with the increase of MgO content. The highest shifts in FB potential reached − 0.85 eV and − 0.65–0.70 eV (vs Standard Calomel Electrode) when MgO content was equal to 10% (w/w) and 10–15% (w/w) for SnO 2 and TiO 2 respectively. In this investigation, interconnection between the negative shift in FB potential and the efficiencies of dye sensitized solar cells based on the prepared materials are discussed.