Conference Agenda

Abstract: 

Layered materials are solids consisting of crystalline sheets with strong in-plane covalent bonds and weak van der Waals out-of-plane interactions. These materials can be easily exfoliated to a single layer, obtaining two-dimensional (2D) materials with radically novel physico-chemical characteristics compared to their bulk counterparts. The field of 2D materials began with graphene and quickly expanded to include semiconducting transition metal dichalcogenides (TMDs). 2D semiconductors exhibit very strong light-matter interaction and exceptionally intense and ultrafast nonlinear optical response, enabling a variety of novel applications in optoelectronics and photonics. Furthermore, stacking 2D materials into heterostructures (HS) offers unlimited possibilities to design new materials tailored for applications. In such HS the electronic structure of the individual layers is well retained because of the weak interlayer van der Waals coupling. Nevertheless, new physical properties and functionalities arise beyond those of their constituent blocks, depending on the type, the stacking sequence and the twist angle of the layers.

This Tutorial will review the key electronic and photonic properties of TMDs and their heterostructures, including strongly bound intralayer excitons, spin-valley locking and valley selectivity. It will also discuss their non-equilibrium properties, such as intralayer exciton formation, their dissociation in HS to form long-lived interlayer excitons, and intervalley scattering processes. It will also discuss the nonlinear optical response of TMDs and approaches to phase match the nonlinear interactions and achieve high conversion efficiencies over unprecedentedly small thicknesses.