Stark Effects of Rydberg Excitons in a Monolayer WSe₂ P-N Junction

Monolayer transitional metal dichalcogenides (TMDCs) are direct bandgap 2D semiconductors that host robust excitons with large binding energy, which leads to superior optical and electronic properties. The large binding energy of excitons enables the formation of Rydberg excitons with a high principal quantum number (n), analogous to Rydberg atoms. In this work, we probe the Rydberg exciton resonances through photocurrent spectroscopy in a monolayer WSe₂ P-N junction devices formed by a split-gate geometry. We reveal the excitonic Stark effect of Rydberg excitons withup to 3. More strikingly, the electric field results in the mixing of the optically bright s states and the dark p and d states, resulting in new bright exciton states with hybridized orbitals that are highly tunable by the in-plane electric field. The excited states exhibit energy shift and splitting as large as 96 meV due to their larger radii, which are orders of magnitude larger than the shift of the ground state (1s) exciton. Our study provides an exciting platform to investigate and engineer Rydberg excitons, paving the way for utilizing Rydberg excitons in the application of quantum sensing.