Unravelling the regulating role of strain engineering on the phonon dispersion, mechanical behavior, and electronic transport properties of pentagonal PtTe2 monolayer

Abstract

Inspired by the experimental synthesis of PdSe2 monolayer with a novel buckling configuration, the mechanical property, phonon dispersion curve, electronic structure, and carrier mobility of anisotropic pentagonal PtTe2 monolayer under strain engineering are systematically investigated by first-principles calculations and deformation potential (DP) theory. Ab initio molecular dynamics (AIMD) simulations show that the pentagonal PtTe2 monolayer is thermally stable at 300 and 600 K. Further phonon dispersion investigation verifies the dynamic stability of pentagonal PtTe2 monolayer under tensile strain, as evidenced by the absence of imaginary frequency. When subjected to tensile strains ranging from 2% to 4% in uniaxial (a- and b-direction) and biaxial directions, the mechanical properties and electronic band structures of pentagonal PtTe2 monolayer exhibit significant changes, leading to the electronic band convergence and decreasing bandgap. The effective mass, elastic constant, deformation potential, and carrier mobility also vary considerably under tensile strains, and a high hole mobility of 3618.51 cm2/V·s is discovered along the a-direction with 3% strain applied in the y-axis. Specifically, the hole mobility of pentagonal PtTe2 monolayer shows large anisotropy ratio, reaching up to 13.99 under 2% tensile strain in the y-axis. Our current work not only unravels the fundamental understanding of the anisotropic mechanical properties, phonon dispersion and electronic transport properties of pentagonal PtTe2 monolayer under strain engineering, but also provides theoretical guidance for applying strain engineering to tune the unique physical properties of two-dimensional materials with pentagonal configurations.