The electronic and optical properties of graphdiyne modulated by adsorption of lithium: A first-principles calculation

Abstract

To explore a novel two-dimensional semiconductor material with tunable bandgap, the adsorptive, electronic, and optical behaviors of lithium (Li) adsorption on graphdiyne (GDY) are studied by employing density functional theory based on first-principles calculations. The results demonstrate that Li adsorption on GDY exhibits high adsorption energy and a proper migration energy barrier, both of which are favorable for facilitating Li adsorption and desorption. Upon Li adsorption, charge transfer occurs from Li to C atoms along the C chain containing alkyne bonds, transforming the systems from p- to n-type semiconductors with the band gap decreasing slightly. Notably, the flexible adsorption/desorption capability of Li on GDY enables an adjustable and reversible change of decreasing/increasing the band gap through the change of the external field. Meanwhile, Li migration primarily occurs between the equivalent A sites, preserving the stable semiconductor characteristics of the system during the Li migration process. Additionally, the absorption coefficient and reflectivity for GDY with Li adsorption decrease in the infrared and visible regions, while maintaining high in the near ultraviolet range. In summary, GDY is not only a promising candidate for fast-charging/discharging Li-ion batteries, but also provides innovative valuable insights for applications in tunable optoelectronic devices.