Effect of Mg content on electronic structure, optical and structural properties of amorphous ZnO nanoparticles: A DFTB study

In this work, we perform a theoretical analysis of structural, electronic, and optical properties of pure and Mg-doped amorphous ZnO nanoparticles (a-ZnO NPs) using DFTB method. Our results show that Zn atoms are more preferential for Mg atoms than for O atoms because the number of Mg[sbnd]Zn bonds is greater than that of Mg[sbnd]O. The rise in the content of Mg in a-ZnO NPs leads to an increase of Mg–Zn and Mg[sbnd]O interactions. Mg atoms prefer to locate near the center of a-ZnO NP, but Zn and O atoms nearly preserve their positions which is compatible with radial distribution function peaks. The orbital energies display a decrease in the energy gap from 3.592 to 3.546 eV while increasing Mg content. The LUMO level is also significantly shifted to higher energies. The results also reveal that the performance of pure a-ZnO NP can be enhanced with a subsequent increase in Mg content.