Electronic and optical properties of Au and Ag doped LiNbO3 from first principles study

Using the first-principles calculation, the electronic and optical properties of Ag and Au doped LiNbO3 are investigated. The first-principles calculation in this work is implemented using CASTEP computer code with GGA-PBE exchange–correlation. The calculated band gap of pure LiNbO3 was observed at 3.547 eV and for doped LiNbO3, the band gap shows a reduction in the band gap value. For Au-doped LiNbO3 shows a value of 1.120 eV while Ag-doped LiNbO3 give a band gap of 0.708 eV. The density of states is calculated to analyze the effect of Au and Ag doping on the electronic properties and absorption spectra. The results show a significant shift toward visible region in the optical absorption edge of Au and Ag doped LiNbO3 compared to pure LiNbO3. The dielectric constant for pure and doped structures are calculated. The enhancement in optical absorption of Ag and Au doped LiNbO3 making it a promising material for photovoltaic and photocatalyst application.