Domain-size effect on the electronic properties of two-dimensional MoS2/WS2

In view of the wreath of potential functionalities two-dimensional (2D) transition-metal dichalcogenides can offer, we study here tuning pathways of 2D lateral arrangements of structures. Specifically, we have systematically doped a pristine 2D MoS2 with WS2 domains of varying sizes. The resulting materials made of MoS2 with WS2 have distinct structural, electronic, and optical properties, which we analyze in detail. By including spin-orbit coupling in our quantum mechanical calculations, we were able to resolve the band structure of these lateral structures. Our analysis reveals a decrease in the band gap from MoS2 and WS2 to MoS2/WS2. The results underline the nature and role of the d(z2) and d(x2-y2) orbitals in the pristine and hybrid 2D structures, respectively, while indicating the possibility of a charge transfer from W to Mo atoms within the 2D hybrid structures. The dielectric matrix computed using the Bethe-Salpeter equation significantly affects the imaginary dielectric function and hence the absorption spectra of the lateral structures. In the end, we discuss the relevance of our work in paving a pathway for a selective tuning of the optoelectronic properties of 2D lateral heterostructures in view of optoelectronic applications.