Structural, Electronic, and Optical Properties of Ag-Doped ZnO Nanowires: First Principles Study

First-principles calculations have been performed to determine the effects of Ag doping to the structural, electronic, and optical properties of ZnO NWs. The calculated formation energies are very low for Ag dopants at substitutional-Zn sites (both under low and high Ag concentration), but rather high at substitutional-O and interstitial sites under O-rich conditions. The Ag Zn and 2Ag Zn defects all prefer the edge of the NW and the formation energy of 2Ag Zn in the favorable O-rich conditions is only 0.40 eV. The calculated acceptor levels of Ag Zn and 2Ag Zn ones are 0.60 and 0.44 eV respectively, indicating Ag may be a good candidate for producing p-type ZnO NW. From the optical properties calculations, strong absorptions have been found in the visible-light region for both the 2Ag Zn and Ag O -doped ZnO NWs. It provides evidence that, except for the usage as short-wavelength optoelectronic devices, Ag-doped ZnO NWs could also display potential application for photocatalysis due to the increase of the visible-photocatalytic activity.