Enhanced excitonic features in an anisotropic ReS/WSe heterostructure.

Two-dimensional (2D) semiconductors have opened new horizons for future optoelectronic applications through efficient light-matter and many-body interactions at quantum level. Anisotropic 2D materials like rhenium disulphide (ReS) present a new class of materials with polarized excitonic resonances. Here, we demonstrate a WSe/ReS heterostructure which exhibits a significant photoluminescence quenching at room temperature as well as at low temperatures.

Visualizing Orbital Content of Electronic Bands in Anisotropic 2D Semiconducting ReSe.

Many properties of layered materials change as they are thinned from their bulk forms down to single layers, with examples including indirect-to-direct band gap transition in 2H semiconducting transition metal dichalcogenides as well as thickness-dependent changes in the valence band structure in post-transition-metal monochalcogenides and black phosphorus. Here, we use angle-resolved photoemission spectroscopy to study the electronic band structure of monolayer ReSe, a semiconductor with a distorted 1T structure and in-plane anisotropy. By changing the polarization of incoming photons, we demonstrate that for ReSe, in contrast to the 2H materials, the out-of-plane transition metal d and chalcogen p orbitals do not contribute significantly to the top of the valence band, which explains the reported weak changes in the electronic structure of this compound as a function of layer number.