Tuning the band gap and optical spectra of monolayer penta-graphene under in-plane biaxial strains

Using first principles calculations, structural, electronic and optical properties of monolayer penta-graphene (MPG) have been studied under different types of in-plane biaxial strains at different magnitudes. The results exhibit that MPG structure under small magnitude of biaxial compressive and tensile strains are more stable than those with large magnitude of strains. It is found that free- strained MPG is an indirect band-gap semiconductor with a band gap of 2.22 eV using PBE functional, approximately equal to those of GaN and ZnO. Appling tensil strain slightly increases the bang gap of MPG, while exerting compresive tensile reduces it. The linear photon energy-dependent dielectric functions and related optical properties including refraction index, real part of conductivity and electron energy-loss spectrum (EELS) were also computed and discussed. The optical calculations illustrate that applying tensile and compressive strains on MPG result in blue and red shift in optical spectra. The results obtained from our calculations are beneficial to practical applications of these strained MPG structures in optoelectronics and electronics.