Tailoring the band gap of GaN codoped by VO for enhanced solar energy conversion from first-principles calculations

The electronic structure of a novel photocatalyst material designed in silico via co-doping of GaN by vanadium and oxygen has been investigated using the DFT + U method. The results show that this codoping approach leads to reduction of the band gap, along with significantly enhanced carrier mobility and photocatalytic activity in visible-light region, which is beneficial towards applications in solar energy conversion as well solar-assisted photocatalysis. Formation energies indicate that co-doping with anions is energetically favorable for cation mono-doping. Codoping by vanadium and oxygen in GaN shifts the Fermi level into the conduction band, resulting in increased carrier mobility and density.

► The VO codoping reduces significantly the formation energy, resulting in substantially enhanced thermodynamic stability.
► Band gap narrowing in VO codoped GaN can extend the absorption edge to the visible-light region.
► Non-compensated codoping of GaN by V and O serves to enhance carrier mobility.