Events

Dielectric control of exciton transport and correlated states in two-dimensional materials

Presented By: Haowen Su

Abstract:
The electronic and optical behavior of two-dimensional (2D) materials can be profoundly influenced by their surrounding environment, making them ideal candidates for post-synthetic tuning of their functionality. My study explores dielectric engineering as a versatile and scalable approach to modulate excitonic and electronic properties in 2D materials, through both local inhomogeneities and periodic structures. We first demonstrate that nanobubbles—nanoscale dielectric inhomogeneities—can control exciton transport in the 2D semiconductor bilayer tungsten diselenide (WSe₂). Using ultrasensitive spatiotemporally resolved optical scattering microscopy, we directly visualize exciton funneling and trapping into these regions at room temperature, driven by momentum-indirect (dark) excitons whose energies are more sensitive to dielectric perturbations than bright excitons. We then propose the use of self-assembled nanoparticles to create highly ordered dielectric superlattices interfaced directly with 2D materials. This bottom-up alternative to moiré materials enables unprecedented flexibility in the design of superlattice period, spatial scale, geometry, and gate tunability, towards the realization of correlated electronic phenomena that are not realizable in currently-used platforms. Together, these results highlight dielectric engineering as a powerful method to control exciton transport and correlated electronic states in 2D materials, offering new pathways to design and control functional quantum materials through post-synthetic modifications.