The Decisive Role Of Interlayer Ionic Couplings For The Electronic Properties Of Two-dimensional Led Electayerrides

Two-dimensional(2D)layered electrides have attracted significant attention as a new class of 2D materials owing to the presence of unusual excess electrons acting like anions.These electrides are more strongly bound by ionic interactions involving the anionic excess electrons compared with van der Waals layers,which is also critical to the physical and chemical properties of the materials.However,to date,the role of interlayer ionic coupling in determining the properties of 2D electrides has been mostly unexplored.Here we use first-principles density functional theory calculations to systematically explore the effects of interlayer ionic interactions on the electronic properties of various existing and proposed layered electrides.A higher density of anionic electrons in the interlayer spacing leads to stronger localization and interlayer coupling strength,which induces a Stoner-type magnetic instability.In-plane strain can dramatically modify the configuration of anionic electrons,thereby enabling strain engineering of the electrides.Strikingly,the work function and interlayer binding energy of the layered electrides are distinctly related,which is in stark contrast to those of van der Waals materials.Besides,we suggest Sr2N and Ba2N as promising candidates for new 2D materials owing to their low interlayer binding energies and stable monolayer forms.This work will not only deepen our understanding of the fundamental properties of layered electrides,but also stimulate further researches in this field.