Effect of Biaxial Strain on Structural, Electronic, and Thermal Transport Properties of Twin Graphene: A Comparative Study with γ-graphyne

The existence of a variety of two-dimensional (2D) carbon allotropes with different carbon frameworks has provided an unprecedented platform to explore novel properties and potential applications beyond graphene. In this work, the strain effects on the structural, electronic, and thermal transport properties of the γ-graphyne and twin graphene sheets have been systematically clarified through first-principles calculations. Regardless of the geometrical similarities of the two considered 2D carbon allotropes, our results indicate that the acetylenic linkages in the γ-graphyne and the AA-stacked aromatic rings in the twin graphene are capable of resulting in the notable deviations in their electronic and thermal transport properties, as well as the strain-dependent behaviors. Both of the two sheets possess an intrinsic semiconducting nature with a tunable direct bandgap that depends on the biaxial strains. The thermal conductivity of the γ-graphyne is significantly suppressed compared to the twin graphene counterpart. Moreover, the heat transfer of the two sheets can be further enhanced by the tensile strains, and a dramatic increase can be obtained in the strained γ-graphyne sheet. Thus, the effectively tunable electronic and thermal transport properties revealed in this work imply the great potential of the two 2D carbon allotropes, and the comparative study also uncovers the structural effect of the carbon networks on their novel properties and strain responses.