Charge-transfer polaritons in van der Waals heterojunctions

2D polaritonic platforms utilizing hybrid light-matter excitations enable a unique form of experimental inquiry into the optical and electronic phenomena of quantum materials at the nanoscale. In our study, we demonstrate a robust strategy to design new polaritonic platforms based on atomically thin van der Waals materials using the notion of oxidation-activated charge transfer. Taking graphene as a model 2D system, we show the applications of this strategy in controlling the behavior of plasmon polaritons, implementing low-loss nanostructured optical elements, and exploring polaritonic topological transitions in graphene-based van der Waals heterostructures.