Electroluminescence from multi-particle exciton complexes in transition metal dichalcogenide semiconductors.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30979893.
- Also identified by DOI 10.1038/s41467-019-09781-y and PMC identifier 6461636.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Light emission from higher-order correlated excitonic states has been recently reported in hBN-encapsulated monolayer WSe<sub>2</sub> and WS<sub>2</sub> upon optical excitation. These exciton complexes are found to be bound states of excitons residing in opposite valleys in momentum space, a promising feature that could be employed in valleytronics or other novel optoelectronic devices. However, electrically-driven light emission from such exciton species is still lacking. Here we report electroluminescence from bright and dark excitons, negatively charged trions and neutral and negatively charged biexcitons, generated by a pulsed gate voltage, in hexagonal boron nitride encapsulated monolayer WSe<sub>2</sub> and WS<sub>2</sub> with graphene as electrode. By tailoring the pulse parameters we are able to tune the emission intensity of the different exciton species in both materials. We find the electroluminescence from charged biexcitons and dark excitons to be as narrow as 2.8 meV.