Tuning the electronic, phonon, and optical properties by strain-induced on the monolayer transition metal dichalcogenides ASe2 (A = Mo and W)

Abstract

Recently, two-dimensional transition metal dichalcogenides (2D-TMDs) have exhibited diverse state-of-the-art technologies for spintronics, memory storage, and optoelectronic device applications. This work explored the unique electronic, phonon, and optical characteristics of 2D-MoSe2 and 2D-WSe2 based on the Density Functional Theory (DFT). We have proposed two stable 2D-TMDs structures and included the spin-orbit coupling (SOC) effect to examine its impact on their structural properties. These SOC included structures exhibit large band splitting of 190 meV and 470 meV, respectively, appear at the top of the valance bands for 2D-MoSe2 and 2D-WSe2, suggesting promising results for next-generation spintronic devices. In addition, upon applying biaxial strain, the direct to indirect bandgap transition has been identified at a − 5% compressive strain for both 2D-MoSe2 and 2D-WSe2. We have also reported the peaks for real and imaginary values of the dielectric constant, optical absorption, and electron energy loss spectra, which may allow attractive applications for photovoltaic and electroluminescent devices. Under increased tensile strain, the absorption peaks of 2D-ASe2 monolayers gradually increase towards lower energy regions (redshift), while the absorption peaks of corresponding compressive strained structures exhibit blueshift. Moreover, the optical performance and light absorption capacity were greatly enhanced with increased tensile strain, making them promising candidates for digital electronics and optoelectronics device applications.