Atomistic Origin of Photoluminescence Quenching in Colloidal MoS<sub>2</sub> and WS<sub>2</sub> Nanoplatelets.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41762124.
- Also identified by DOI 10.1021/acs.nanolett.5c05893 and PMC identifier 12983361.
- 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
Large chemical tunability and strong light-matter interactions make colloidal transition metal dichalcogenide (TMD) nanostructures particularly suitable for light-emitting applications. However, ultrafast exciton decay and quenched photoluminescence (PL) limit their potential. Combining femtosecond transient absorption spectroscopy with first-principles calculations on MoS<sub>2</sub> and WS<sub>2</sub> nanoplatelets, we reveal that the observed sub-picosecond exciton decay originates from edge-located optically bright hole traps. These intrinsic trap states stem from the metal <i>d</i>-orbitals and persist even when the sulfur-terminated edges are hydrogen-passivated. Notably, WS<sub>2</sub> nanostructures show more localized and optically active edge states than their MoS<sub>2</sub> counterparts, and zigzag edges exhibit a higher trap density than armchair edges. The nanoplatelet size dictates the competition between ultrafast edge-trapping and slower core-exciton recombination, and the states responsible for exciton quenching enhance the catalytic activity. Our work represents an important step forward in understanding exciton quenching in TMD nanoplatelets and stimulates additional research to refine physicochemical protocols for enhanced PL.