Format

Send to

Choose Destination
ACS Nano. 2015 Jan 27;9(1):647-55. doi: 10.1021/nn5059908. Epub 2015 Jan 12.

Observation of excitonic fine structure in a 2D transition-metal dichalcogenide semiconductor.

Author information

1
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371.

Abstract

Two-dimensional (2D) semiconductors, such as transition-metal dichalcogenide monolayers (TMD 1Ls), have attracted increasing attention owing to the underlying fundamental physics (e.g., many body effects) and the promising optoelectronic applications such as light-emitting diodes. Though much progress has been made, intrinsic excitonic states of TMD 1Ls are still highly debated in theory, which thirsts for direct experimental determination. Here, we report unconventional emission and excitonic fine structure in 1L WS2 revealed by electrical doping and photoexcitation, which reflects the interplay of exciton, trion, and other excitonic states. Tunable excitonic emission has been realized in a controllable manner via electrical and/or optical injection of charge carriers. Remarkably enough, the superlinear (i.e., quadratic) emission is unambiguously observed which is attributed to biexciton states, indicating the strong Coulomb interactions in such a 2D material. In a nearly neutral 1L WS2, trions and biexcitons possess large binding energies of ∼ 10-15 and 45 meV, respectively. Moreover, our finding of electrically induced robust emission opens up a possibility to boost the luminous efficiency of emerging 1L TMD light emitting diodes.

KEYWORDS:

biexciton; photoluminescence; transition-metal dichalcogenide; trion; two-dimensional semiconductor

PMID:
25560634
DOI:
10.1021/nn5059908

Supplemental Content

Full text links

Icon for American Chemical Society
Loading ...
Support Center