A simple low temperature synthesis route for ZnO–MgO core–shell nanowires

Abstract

We report a hydrothermal synthesis method for MgO shell coatings directly onto thesurface of ZnO nanowire arrays. The entire process can be carried out below100 °C. The MgO shells are produced by the addition of 10 mM magnesium nitrate with 0.2 Msodium hydroxide in water, resulting in a shell thickness of up to 8 nm, verified by highresolution transmission electron microscopy. The viability of the MgO layer as a functionalelement of optoelectronic devices was tested on solid-state organic hole-transporter baseddye-sensitized solar cells. Incorporation of the MgO shell into the solar cell resulted insubstantive efficiency improvements of over 400% in comparison to the pristine ZnOnanowire based photovoltaics, indicating that electrons can efficiently tunnel through the‘insulating’ MgO shell.