Revealing hidden interlayer excitons in 2D bilayers via hybrid molecular gating

Area of Science:

• Materials Science
• Condensed Matter Physics
• Quantum Optics

Background:

• Heterostructures combining molecules and 2D materials exhibit unique emergent properties.
• Excitons in transition metal dichalcogenides are crucial for understanding optical and electronic phenomena.

Purpose of the Study:

• To investigate exciton behavior in bilayer transition metal dichalcogenides under intense electric fields.
• To explore new physical regimes by achieving high electric field strengths via molecular charge transfer.
• To understand exciton hybridization and Stark splitting in response to strong electric fields.

Main Methods:

• Fabrication of molecular heterostructures with bilayer transition metal dichalcogenides.
• Application of intense electric fields (up to 0.35 V nm⁻¹) using charge transfer from proximal molecules.
• Optical spectroscopy to detect and analyze exciton behavior and energy shifts.

Main Results:

• Achieved electric field strengths twice as high as previously possible in solid-state devices.
• Observed energetic resonance between inter- and intralayer excitons.
• Detected a novel interlayer exciton, visible only at high electric fields due to hybridization with intralayer excitons.
• Measured ultra-strong Stark splitting (> 350 meV) with tunable exciton energies.

Conclusions:

• Intense electric fields enable the study of new physical phenomena in 2D material heterostructures.
• Exciton hybridization and energy levels can be effectively controlled using strong electric fields.
• The findings hold significant potential for the development of advanced optoelectronic devices.