A first-principles study of Janus monolayer MXY (M = Mo, W; X, Y = S, Se, Te)/SiO2 van der Waals heterojunctions for integrated optical fibers

Heterogeneous stacking of silica optical fiber materials and two-dimensional (2D) materials is a very effective strategy to design high-performance optoelectronic devices. Herein, first-principles calculations are performed to study the interface structures of Janus transition metal dichalcogenides (TMDs) monolayers deposited over silicon dioxide (SiO2). A series of van der Waals (vdW) heterostructures based on SiO2 and Janus MXY (M = Mo, W; X, Y = S, Se, Te) monolayers are investigated in geometric, electronic structures and optical properties. Through step-by-step screening, type-I heterojunctions with seven different contact types are investigated to be the best candidates. The interlayer spacing of these selected vdW heterostructures is large, and there is no covalent bond formed at the interface. For different interface contact types, massive electronic interactions are manifested at the Janus TMDs and SiO2 interfaces, indicating the influence of the vdW interactions on the electronic structure of the compound models. In addition, the optical absorption of silica optical fiber materials is enhanced by the composite of 2D Janus TMDs materials. This work could provide theoretical guidelines for the functional properties of the 2D materials’ composite silica optical fibers and contribute to the design of novel optoelectronic devices.