Amplification of Interlayer Exciton Emission in Twisted Transition Metal Dichalcogenides Heterostructures

Transition metal dichalcogenides (TMDC) heterostructures (HS) are obtained by stacking two or more different monolayers (ML). These structures host spatially indirect interlayer excitons (IX) with unique properties that depend on the twist angle and stacking order of two or more MLs [1]. However, the practical applications of IXs are limited by their weak oscillator strength, which leads to a significant reduction in emission. Therefore, innovative solutions to substantially improve the emission of interlayer excitons are desirable. Here we present two concepts to enhance the emission of interlayer excitons in twisted TMDC HSs for future use in nanophotonic devices. One concept is based on advanced WSe2/WSe2/MoSe2 heterotrilayer (HTL) systems. In this system, the interlayer exciton formed in the HTL region exhibits up to a 10-fold increase in photoluminescence yield compared to the heterobilayer (HBL) region on the same sample. Detailed optical and numerical investigations show that the interactions between the three layers significantly contribute to the formation and relaxation mechanisms of interlayer excitons, resulting in the observed luminescence enhancement [1]. The second concept utilizes light-matter interaction of TMDC HSs integrated into chirped distributed Bragg reflectors, which feature energetically separated cavity resonances. This configuration enables cavity-coupled emission of intra and interlayer excitons that are energetically separated in a WSe2/MoSe2 HSs. The chirped microcavity, in combination with TMDC HSs, shows potential for studying moiré physics and enhancing light-matter interactions in TMDC-based devices [2]. Overall, our approaches offer versatile tools for future studies and applications of TMDC HS using innovative layer and cavity designs.<br/><br/>[1] C. C. Palekar et al., 2D Mater. 11, 025034 (2024)<br/>[2] C. C. Palekar et al., arXiv:2311.02509<br/>[3] C. C. Palekar et al., arxiv: 2403.06008