Impact of Polarization Field Architecture on Excitonic Properties of 2D Janus Homobilayers

Two-dimensional (2D) Janus excitonic materials are a novel class of two-faced 2D materials characterized by distinct atomic arrangements in their top and bottom layers. These materials feature different chalcogen atoms on opposite sides of a transition metal layer, creating a unique out-of-plane polarization field (Janus field) due to the differing electronegativity values of these atoms. In this work, we realized 2D Janus homobilayers with controlled Janus field configurations, such as up arrow up arrow and up arrow down arrow, to study the effects of the Janus electric field on band alignment and overall optical emission characteristics. Our results demonstrate that 2D Janus homobilayers exhibit notable changes in excitonic behavior depending on whether the Janus fields are aligned in the same direction or oppose each other. Comparisons between natural and artificial classical TMD homobilayers further illustrated the impact of the Janus field architecture on 2D Janus homobilayer excitonic responses.