Alloy engineering of excitonic properties in TMD monolayers
We investigate monolayer MoS$_{2x}$Se$_{2(1-x)}$ alloys across the full composition range using optical spectroscopy. We demonstrate continuous tuning of the optical gap over $\sim$0.35 eV, accompanied by a systematic reduction of the B--A exciton splitting, in agreement with density functional theory calculations. Temperature-dependent measurements reveal a progressive increase of the average phonon energy from Se-rich to S-rich alloys that follows a simple reduced-mass scaling model. Polarization-resolved spectroscopy further shows a monotonic increase of the circular polarization from nearly zero in MoSe$_2$ to $\sim$15\% in MoS$_2$ at 78 K. The observed evolution of the polarization is attributed to alloy-induced modifications of the electronic structure that modify bright--dark exciton mixing and the associated valley depolarization. These findings establish alloy engineering as an effective strategy for controlling excitonic properties in TMD monolayers.
Authors
- Ioannis Paradisanos (ORCID: https://orcid.org/0000-0001-8310-710X)
- Iann C. Gerber (ORCID: https://orcid.org/0000-0001-5091-2655)
- Adlen Smiri (ORCID: https://orcid.org/0000-0002-8511-9216)
- Georgios Kopidakis (ORCID: https://orcid.org/0000-0002-5275-0060)
- George Kioseoglou (ORCID: https://orcid.org/0000-0001-7276-4403)
- E. Katsipoulaki (ORCID: https://orcid.org/0009-0009-4872-5258)
- Konstantinos Mourzidis (ORCID: https://orcid.org/0009-0008-6376-694X)
- Danae Katrisioti (ORCID: https://orcid.org/0009-0000-9346-862X)
- Takashi Taniguchi (ORCID: https://orcid.org/0000-0002-1467-3105)
- Kenji Watanabe (ORCID: https://orcid.org/0000-0003-3701-8119)
- Zdenek Sofer (ORCID: https://orcid.org/0000-0002-1391-4448)
- Emmanuel Stratakis
- Xavier Marie
- Panagiotis Spiliotakis
- Gang Wang
Institutions
- Beijing Institute of Technology (CN)
- Centre National de la Recherche Scientifique (FR)
- University of Crete (GR)
- Institut Universitaire de France (FR)
- National Institute for Materials Science (JP)
- Laboratoire de Physique et Chimie des Nano-Objets (FR)
- Université de Toulouse (FR)
- Institut National des Sciences Appliquées de Lyon (FR)
- Foundation for Research and Technology Hellas (GR)
- University of Chemistry and Technology, Prague (CZ)
Publication Details
- Journal
- Physical Review Materials
- Published
- 2026-10-26
- DOI
- https://doi.org/10.1103/m7kc-8q5v
- Primary Topic
- 2D Materials and Applications
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Centre Informatique National de l’Enseignement Supérieur
- Equipex
- Agence Nationale de la Recherche
- Japan Science and Technology Corporation
- Ministry of Education, Culture, Sports, Science and Technology
- Ministerstvo Školství, Mládeže a Tělovýchovy
- Dynasty Foundation
- Grand Équipement National De Calcul Intensif
- HORIZON EUROPE Framework Programme
- Core Research for Evolutional Science and Technology