Ultrafast Recombination Dynamics under Lateral Confinement and Cryogenic Temperatures in Colloidal MoS₂

authored by

André Philipp Frauendorf, André Niebur, Dominik Rudolph, Michael Oestreich, Jannika Lauth, Jens Hübner

Abstract

Colloidal synthesis opened up a versatile way to tailor two-dimensional transition metal dichalcogenides. In particular, the huge oscillator strength of excitons in colloidal MoS₂ makes the material appealing for excitonic devices. In this context, we studied ultrafast excitons with transient absorption (TA) spectroscopy in MoS₂ nanosheets (NSs, 22 ± 9 nm) and nanoplatelets (NPLs, 8 ± 4 nm) with NPLs providing additional lateral confinement of excitons in the structures. Carrier relaxation mechanisms are identified by extending the TA setup with a custom micro cryostat and by extracting time-dependent line shapes. The exciton lifetime in MoS₂ NSs almost doubles from 12 to 22 ps by cooling the samples from 295 to 9 K, which is attributed to phonon scattering. Temperature-dependent recombination dynamics are found for the sparsely studied C and D excitons, thus covering the full visible spectrum by time-resolved characterization. For smaller MoS₂ NPLs, the A exciton signature reappears at cryogenic temperatures, allowing laterally confined excitons in MoS₂ to be extensively studied for the first time.

Organisation(s)

Institute of Solid State Physics
Institute of Physical Chemistry and Electrochemistry
PhoenixD: Photonics, Optics, and Engineering - Innovation Across Disciplines
Laboratory of Nano and Quantum Engineering

External Organisation(s)

University of Tübingen

Type

Article

Journal

Journal of Physical Chemistry C

Volume

128

Pages

16597–16606

No. of pages

10

ISSN

1932-7447

Publication date

03.10.2024

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials, General Energy, Physical and Theoretical Chemistry, Surfaces, Coatings and Films

Electronic version(s)

https://doi.org/10.1021/acs.jpcc.4c04581 (Access: Open)