Analysis of localized excitons in strained monolayer WSe₂ by first principles calculations

Abstract

In this work we gain insight by first principles calculations into the tunability of electronic and optical properties upon introduction of a wrinkle in monolayer WSe2.

Funneling and spin-orbit coupling in transition metal dichalcogenide nanotubes and wrinkles

“…Yet, since the band extrema also have small differences in the momentum direction which complicate the situation, further studies using, e.g., the Bethe-Salpeter equation to describe the excitonic states are needed which are -at the moment -however only possible for the smallest systems of our study. [71] Nevertheless, as shown previously, the changes of the local band gap give a very good estimate of the shifts of excitonic peaks. [67][68][69] Another important effect which will influence the dynamics of excitons, are the internal electric fields which are induced by the curvature [72].…”

“…Furthermore, the changes of the electronic structure in these wrinkles leads to funneling, i.e., a preferential emission of light from certain spatial position along the wrinkle. [28,30,[37][38][39][40] However, the local strain in such samples is far from being homogeneous and the comparison with calculations of homogeneously strained systems might be misleading. Understanding this (local) inhomogeneous strain in 2D materials requires further research due to the vast opportunities for future applications such as polarized single photon emitters [41,42] and flexible optoelectronics [23].…”

Electronic properties of MoSe2 nanowrinkles

“…16 These nanostructures offer the opportunity to further tune the characteristics of the TMDCs, especially concerning exciton manipulation [17][18][19][20][21] and quantum emission. 7,15 However, the complex interplay between structural characteristics, including strain and curvature, and electronic and optical response 19,[22][23][24][25] does not facilitate the identification of a straightforward rationale to engineer their properties.…”

“…This is very important in the case of rippled TMDCs, where the large number of degrees of freedom in play makes the effects of curvature, strain, and local deformations particularly hard to disentangle. 19,22 Moreover, in contrast to classical models, which are useful to reveal the mechanical characteristics of peculiar low-dimensional topologies 14,45 and to connect them with macroscopic experimental variables, a quantum-mechanical description of the electronic structure is able to provide microscopic insight into these materials. 19,22,23,46 In this work, we investigate from first principles the electronic properties of MoSe 2 nanowrinkles with varying curva-ture and strain.…”

“…19,22 Moreover, in contrast to classical models, which are useful to reveal the mechanical characteristics of peculiar low-dimensional topologies 14,45 and to connect them with macroscopic experimental variables, a quantum-mechanical description of the electronic structure is able to provide microscopic insight into these materials. 19,22,23,46…”