We report a first-principles study on the elastic, vibrational, and electronic properties of the recently synthesized phosphorene. By calculating the Grüneisen parameters, we evaluate the frequency shift of the Raman and infrared active modes via symmetric biaxial strain. We also study a strain-induced semiconductor-metal transition, the gap size, and the effective mass of carriers in various strain configurations. Furthermore, we unfold the emergence of a peculiar Dirac-shaped dispersion for specific strain conditions including the zigzag-oriented tensile strain. The observed linear energy spectrum has distinct velocities corresponding to each of its linear branches and is limited to the $\Gamma \text{−}X$ direction in the first Brillouin zone.

In this paper, the effect of biaxial strain on the mobility of single-layer transition metal dichalcogenides (MoS ₂ , MoSe ₂ , WS ₂ , and WSe ₂ ) is investigated by accounting for the scattering from intrinsic phonon modes, remote phonons, and charged impurities. Ab initio simulations are employed to study a strain-induced effect on the electronic band structure, and the linearized Boltzmann transport equation is used to evaluate the low-field mobility. The results indicate that tensile strain increases the mobility. In particular, a significant increase in the mobility of single-layer MoSe ₂ and WSe ₂ with a relatively small tensile strain is observed. Under a compressive strain, however, the mobility exhibits a nonmonotonic behavior. With a relatively small compressive strain, the mobility decreases and then it partially recovers with a further increase in the compressive strain.

We theoretically investigate the thermoelectric properties of zigzag graphene nanoribbons in the presence of extended line defects, substrate impurities, and edge roughness along the nanoribbon’s length. A nearest-neighbor tight-binding model for the electronic structure and a fourth nearest-neighbor force constant model for the phonon bandstructure are used. For transport, we employ quantum mechanical non-equilibrium Green’s function simulations. Starting from the pristine zigzag nanoribbon structure that exhibits very poor thermoelectric performance, we demonstrate how after a series of engineering design steps the performance can be largely enhanced. Our results could be useful in the design of highly efficient nanostructured graphene nanoribbon–based thermoelectric devices.

The thermoelectric properties of graphene-based antidot lattices are theoretically investigated. A third nearest-neighbor tight-binding model and a fourth nearest-neighbor force constant model are employed to study the electronic and phononic band structures of graphene antidot lattices with circular, rectangular, hexagonal, and triangular antidot shapes. Ballistic transport models are used to evaluate transport coefficients. Methods to reduce the thermal conductance and to increase the thermoelectric power factor of such structures are studied. Our results indicate that triangular antidot lattices have the smallest thermal conductance due to longer boundaries and the smallest distance between the neighboring antidots. Among them, iso-triangular antidot lattices have also a large power factor and as a result a large figure of merit.