Understanding the Effects of Dielectric Property, Separation Distance, and Band Alignment on Interlayer Excitons in 2D Hybrid MoS2/WSe2 Heterostructures

TL;DR

This study investigates how dielectric properties, separation distance, and band alignment influence interlayer excitons in 2D MoS2/WSe2 heterostructures, revealing key mechanisms for modulating exciton behavior in optoelectronic applications.

Contribution

Introduces organic-layer-embedded hybrid heterostructures to analyze interlayer exciton binding energy and modulation mechanisms in 2D TMDC heterostructures.

Findings

Dielectric screening decreases with organic molecules, causing a blueshift in emission.

Band alignment affects charge transfer and exciton emission energies.

Electron or hole trapping molecules can suppress interlayer exciton formation.

Abstract

Two dimensional (2D) van der Waals heterostructures from transition metal dichalcogenide (TMDC) semiconductors show a new class of spatially separate excitons with extraordinary properties. The interlayer excitons (XI) have been studied extensively, yet the mechanisms that modulate XI are still not well understood. Here, we introduce several organic-layer-embedded hybrid heterostructures, MoS2/organic/WSe2, to study the binding energy of XI. We discover that the dielectric screening of the quasi-particle is reduced with organic molecules due to decreased dielectric constant and greater separation distance between the TMDC layers. As a result, a distinct blueshift is observed in interlayer emission. We also find that the band alignment at the heterointerface is critical. When the organic layer provides a staggered energy state, interlayer charge transfer can transition from tunneling to band-assisted transfer, further increasing XI emission energies due to a stronger dipolar interaction. The formation of XI may also be significantly suppressed with electron or hole trapping molecules. These findings should be useful in realizing XI-based optoelectronics.