Functionalizing LAyered 2D nanoflakes for Tailored optoelectronics

• Applicant: Professor Dr. Carsten Rockstuhl
• Subject Area: Theoretical Condensed Matter Physics ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 465163297

2D materials provide a versatile playground for nanoscale optoelectronics: different single-atom thick materials offer a great variety of optical properties. Effects of interest supported by such materials are a unique optical absorption, the transduction or emission of light from microwave to ultraviolet frequencies, the ability to control the charge mobility by ultrafast gating, the incorporation of defects to emit photons for quantum applications, or novel opportunities for electronics.Whole new potentials unfolds when different monolayered materials are stacked, forming artificial heterostructures of properties controllable by design. For example, combining a graphene with a hexagonal boron nitride monolayer allows to modulate graphene's electronic structure and its energy band. Heterostructures combining different 2D materials make microscaled light emitting and optoelectronic devices. Topological polaritons occur in bilayer transition metal dichalcogenides and a transition from a hyperbolic to a non-hyperbolic dispersion relation for phonon polaritons occurs in twisted MoO3 bilayers.While some of these properties have been explored for infinite layers, our project explores the optoelectronic potential of 2D material flakes and flake-based heterostructures. Unique to our work is the description with a tight-binding methodology to accommodate effects related to the quantum confinement in the nanostructures, combined with a description in terms of time-dependent density matrix. A master equation accounts for the evolution of flake electrons upon illumination with external light sources or electric gating, including effects resulting from electron-electron interactions or presence of defects. We will-develop a quantum-mechanical framework to model electron dynamics under electromagnetic illumination in different material flakes and apply it to understand their optoelectronic properties at the fundamental level.-extend this framework to allow stacking of elements made of different materials. The extended method will be applied to design devices of tunable electronic properties and optical response, e.g. electro-optic modulators, polaritonic circuits, or optical sensors.-perform a comprehensive study of electron dynamics in these structures and their applications for optics and optoelectronics.The applications we concentrate on are nanoflake-based light emitting devices with classical characteristics or with quantum statistics. By combining or rotating several material flakes we will engineer the spectral properties of these sources and their directionality. We will explore how the energy characteristics of such sources based on nanoflakes or ribbons rely on external electric gating, and exploit that information to develop our contribution further towards miniaturized electro-optic modulators. We will study the electron tunnelling through insulating barriers in nanoflakes or ribbons for nanoscaled tunable tunnel transistors.

• DFG Programme: Research Grants
• International Connection: Poland
• Cooperation Partner: Dr. Karolina Slowik