Electronic, optical, and adsorption properties of Li-doped hexagonal boron nitride: a GW approach

This study employs quasiparticle-corrected DFT calculations to explore the electronic, optical, and surface adsorption properties of Li-doped hexagonal boron nitride (h-BN^Li) monolayers. The results reveal that Li doping introduces two defect states into the wide band gap of the monolayer, reducing the band gap from 5.73 eV to 3.72 eV at the K-Γ point of the Brillouin zone. Using the GW approach to incorporate quasiparticle energies demonstrates a distinct advantage over conventional DFT, leading to qualitative shifts in band alignment across the Brillouin zone. Additionally, we identify intragap transitions driven by these defect states, resulting in a significant red shift in the optical gap, decreasing it from 5.73 eV to 1.61 eV in the doped monolayer. Moreover, Li doping enhances the detection of carbon-based gas molecules, raising the surface adsorption energy by -0.42 eV and -0.45 eV compared to the pristine monolayer. These findings hold substantial promise for the application of h-BN^Li in electronic, optoelectronic, optical, and sensing devices, effectively subjugating the challenge posed by its wide band gap.