January 7, 2025
Journal Article

Tunable Localized Charge Transfer Excitons in Nanoplatelet-2D chalcogenide van der Waals Heterostructures

Abstract

Observation of interlayer, charge-transfer (CT) excitons in van der Waals heterostructures (vdWHs) based on 2D-2D systems has been well investigated. While conceptually interesting, these charge transfer excitons are highly delocalized and spatially localizing them requires twisting layers at very specific angles. This issue of localizing the CT excitons can be overcome via making nanoplate-2D material heterostructure (N2DH) where one of the components is a spatially quantum confined medium. Here, we demonstrate the formation of CT excitons in a 2D/quasi-2D system comprising MoSe2 and WSe2 monolayers and CdSe/CdS based core/shell nanoplates (NPLs). Spectral signatures of CT excitons in our N2DHs were resolved locally at the 2D/single-NPL heterointerface using tip-enhanced photoluminescence (TEPL) at room temperature. By varying both the 2D material, the shell thickness of the NPLs, and applying an out-of-plane electric field, the exciton resonance energy was tuned by up to 100 meV. Our finding is a significant step towards the realization of highly tunable N2DH-based next generation photonic devices.

Published: January 7, 2025

Citation

Rahaman M., E. Marino, A.G. Joly, C.E. Stevens, S. Song, A. Alfieri, and Z. Jiang, et al. 2024. Tunable Localized Charge Transfer Excitons in Nanoplatelet-2D chalcogenide van der Waals Heterostructures. ACS Nano 18, no. 23:15185–15193. PNNL-SA-194947. doi:10.1021/acsnano.4c03260