Electronic, optical, mechanical, and thermal properties of diphenylacetylene-based graphyne nanosheet using density functional theory.

In this paper, the structural stability, electronic, optical, mechanical, and thermal properties of diphenylacetylene-based graphyne (DPAG) nanosheet are investigated using first-principle calculations based on density functional theory (DFT). The absolute value of the calculated cohesive energy reveals that DPAG nanosheet is a structurally stable two-dimensional material. Also, in the results of phononic dispersion curves, the absence of imaginary frequencies confirms the dynamic stability of this novel material. In addition, the theoretical electronic band structure and density of states reveal the semiconducting nature of DPAG nanosheet. The optical analysis shows that the first absorption peaks of the imaginary and real parts of dielectric constants along the in-plane and out-of-plane polarizations of DPAG monolayer occur in the visible range of the electromagnetic spectrum. On the other hand, the DPAG nanosheet exhibits orthotropic elastic behavior with four independent constants comparable with the data of similar materials available in the literature. Moreover, DFT calculations of the lattice thermal conductivity of DPAG reveals an anomalously very low thermal conductivity of this nanosheet showing its perfect thermal non-conductivity. Our results provide deep insights into the potential applications of DPAG nanosheet for the design of new optoelectronic/nanoelectronic devices.