Electronic and optical properties of ?-graphyne under biaxial strain

Compared to pure sp(2)-sp(2) hybridized structure graphene, two-dimensional monolayer ?-graphyne is a new all-carbon material with abundant carbon chemical bonds. The study on the electronic especially optical properties ?-graphyne under a strain has been rarely involved. Here we theoretically study the electronic and optical properties of ?-graphyne under biaxial strain based on first-principles calculations. We find that the ?-graphyne can sustain up to 9% large biaxial strain maintaining structural stability. The band gap increases gradually as the strain increases, and we provide the differential charges to investigate the possible intrinsic mechanism of the band gap variation. Further, we present the real and imaginary parts of the dielectric function, the reflectivity, absorption coefficient and transmission as a function of the photon energy under the strain. In the visible light range, it is interesting to find that all the peaks increase with their positions shifting to left (red-shift) for the real and imaginary parts of the dielectric function, the reflectivity and absorption coefficient as the strain increases, while the other peaks decrease gradually. Our findings may provide a further understanding on the electronic and optical properties of ?-graphyne and may be useful to design optoelectronic devices based on it.