Excitons in van der Waals heterostructures: The important role of dielectric screening

van der Waals heterostructures, created by stacking two-dimensional materials, represent a novel and largely unexplored class of materials with very interesting optoelectronic properties. Excitons, strongly bound electron-hole pairs, play a crucial role in determining these properties, especially in 2D materials where the electron-hole binding is strong. However, a complete understanding of excitonic effects in 2D layered materials, i.e., when the electronic system transitions from a 2D geometry to a 3D one, is still missing. Here, the authors present a first-principles based multiscale method that attempts to fill this gap. With the help of their framework, one can predict the optoelectronics properties of van der Waals heterostructures and make a closer connection between the available theoretical models and experimental measurements in these materials.