Controlled dynamic variation of interfacial electronic and optical properties of sodium-intercalated silicene/hBN heterostructure

Dynamical variation of the properties of materials in a controllable and reversible manner is highly desirable for obtaining next-generation multifunctional materials. This work involves modulation of the interfacial electronic and optical properties of Na-intercalated two-dimensional (2D) van der Waals heterostructure (vdW-HS) consisting of puckered silicene and hexagonal boron nitride (hBN) through layer-sliding. Anifty modeling of silicene/hBN vdW-HS significantly minimized the latticemismatch between silicene and hBN from 35.32 to 2.97%. Afterwards, most stable site for Na at the interface is screened out. To demonstrate the variation of properties dynamically, silicene layer is slided over hBN in regular intervals, and various parametric quantities relating to physical properties are calculated with PW-LDA and PBE-GGA functionals repetitively and compared. To check the stability of vdW-HS along the sliding pathway relative total energies, vdW interactions and vdW-gaps are computed. Planar average charge density difference (Delta rho, charge transfer (Delta Q), and interface dipole moment (Delta mu) are also calculated and varied to study the interfacial electronic properties due to layer-sliding and intercalation. It is found that Delta Q at the interface for fully vdW-HS is 15% and 12% higher than the un-slided vdW-HS with PW-LDA and PBE-GGA, respectively. A number of optical properties relating to the intercalated silicene/hBN vdW-HS such as real [epsilon(1)(omega)] and imaginary [epsilon(2)(omega)] parts of complex dielectric function, electron energy loss function [L(omega)], diagonal components of dielectric tensor [epsilon(i omega)], and optical joint density of states [J (omega)] have been discussed in detail. The maximum absorption takes place for in-plane epsilon(2)(omega) at around 3.63/3.71, 3.63/3.96, and 3.68/3.68 eV with PW-LDA/PBE-GGA for un-slided, half slided, and fully slided silicene/hBN vdW-HS, respectively. Polarization and energy losses are reduced whereas optical absorption is increased by 13.69 and 16.23% in the case of PW-LDA and PBE-GGA for fully slided vdW-HS as compared with the un-slided vdW-HS. Proposed layer-sliding method can be developed as a general approach for real-time fine-tuning of the properties of layered materials.