Optical excitations and thermoelectric properties of two-dimensional holey graphene
Deobrat Singh, Vivekanand Shukla, Rajeev Ahuja
Abstract
Recently, holey graphene (HG) was synthesized successfully at atomic precision with regard to hole size and shape, which indicates that HG has interesting physical and chemical properties for energy and environmental applications. The shaping of the pores also transforms semimetallic graphene into semiconductor HG, which opens new doors for its use in electronic applications. We investigated systematically the structural, electronic, optical, and thermoelectric properties of HG structure using first-principles calculations. HG was found to have a direct band gap of 0.65 eV (PBE functional) and 0.95 eV (HSE06 functional); the HSE06 functional is in good agreement with experimental results. For the optical properties, we used single-shot ${G}_{0}{W}_{0}$ calculations by solving the Bethe-Salpeter equation to determine the intralayer excitonic effects. From the absorption spectrum, we obtained an optical gap of 1.28 eV and a weak excitonic binding energy of 80 meV. We found large values of thermopower of 1662.59 $\ensuremath{\mu}\mathrm{V}$/K and a better electronic figure of merit, ${ZT}_{e}$, of 1.13 from the investigated thermoelectric properties. Our investigations exhibit strong and broad optical absorption in the visible light region, which makes monolayer HG a promising candidate for optoelectronic and thermoelectric applications.