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Nano Research

Article Title

Local modulation of excitons and trions in monolayer WS2 by carbon nanotubes

Keywords

WS2, single-walled carbon nanotube (SWNT), mixed dimensional heterostructure, excitons, trion

Abstract

Mixed dimensional van der Waals (vdW) heterostructures constructed by one-dimensional (1D) and two-dimensional (2D) materials exhibit extra degree of freedom to modulate the electronic and optical properties due to the combination of different dimensionalities. The charge transfer at the interface between 1D and 2D materials plays a crucial role in the optoelectronic properties and performance of the heterostructure-based devices. Here, we stacked single-walled carbon nanotubes (SWNTs) on monolayer WS2 for a mixed dimensional vdW heterostructure, and investigated the local modulation of excitions and trions in WS2 by SWNTs. Different directions of charge transfer between SWNTs and WS2 are evidenced by the photoluminescence (PL) spectra of WS2. The PL intensity can be either enhanced or weakened by individual SWNTs. In our work, the PL intensity of WS2 is enhanced and the exciton peak position heterostructure is red-shifted about 3 meV due to the charge transfer from WS2 to an individual SWNT (SWNT#1). The change of PL by another SWNT (SWNT#2) can not be well-resolved in far-field, but scanning near-field optical microscope (SNOM) measurements show that the PL intensity of WS2 is weakened by the SWNT. The peak position of exciton is blue-shifted by ~ 1 meV while that of trion is redshifted by ~ 1 meV due to the charge transfer from the SWNT to WS2. These results give insight into the charge transfer at the interface of SWNT/WS2 heterostructure, and can be useful for design of optoelectronic devices based on mixed dimensional vdW heterostructures.

Graphical Abstract

Publisher

Tsinghua University Press

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