Ultrafast Dynamics of Rydberg Excitons and Their Optically Induced Charged Complexes in Encapsulated WSe<sub>2</sub> Monolayers
Quantum confinement and reduced dielectric screening lead to strong excitonic effects in atomically thin transition metal dichalcogenides (TMDs). Encapsulation of TMD monolayers in hexagonal boron nitride (hBN) unveils the excitonic Rydberg series below the free particle bandgap. The nonequilibrium response and the dynamics of these higher order exciton states and their multiparticle complexes remain almost unexplored. Here we use ultrafast pump-probe optical microscopy to measure the dynamics of excited-state (2s) excitons in hBN-encapsulated monolayer WSe<sub>2</sub>. 2s excitons form through an ultrafast relaxation process from high-energy states and exhibit longer decay dynamics than ground state excitons due to their higher spatial extension. We detect light-induced formation of 2s trions with significant oscillator strength and faster decay dynamics than 2s excitons, attributed to an intra-excitonic Auger effect causing an additional decay channel. Our results shed light on the dynamics of excited state excitons in TMDs and their interactions with free carriers.
Authors
- Osman Balcı (ORCID: https://orcid.org/0000-0003-2766-2197)
- Tanweer Ahmed (ORCID: https://orcid.org/0000-0002-5921-8405)
- Sefaattin Tongay (ORCID: https://orcid.org/0000-0001-8294-984X)
- V. Shahnazaryan (ORCID: https://orcid.org/0000-0001-7892-0550)
- Takashi Taniguchi (ORCID: https://orcid.org/0000-0002-1467-3105)
- Kenji Watanabe (ORCID: https://orcid.org/0000-0003-3701-8119)
- Giulio Cerullo (ORCID: https://orcid.org/0000-0002-9534-2702)
- Armando Genco (ORCID: https://orcid.org/0000-0002-1292-2614)
- Alisson R. Cadore (ORCID: https://orcid.org/0000-0003-1081-0915)
- Bárbara L. T. Rosa (ORCID: https://orcid.org/0000-0001-9433-3532)
- Habib Rostami (ORCID: https://orcid.org/0000-0002-9521-1008)
- Andrea C. Ferrari (ORCID: https://orcid.org/0000-0003-0907-9993)
- Evgeny M. Alexeev (ORCID: https://orcid.org/0000-0002-8149-6364)
- James Kerfoot (ORCID: https://orcid.org/0000-0002-6041-4833)
- Stefano Dal Conte (ORCID: https://orcid.org/0000-0001-8582-3185)
- Oleg Dogadov
- Chiara Trovatello (ORCID: https://orcid.org/0000-0002-8150-9743)
Institutions
- ITMO University (RU)
- National Institute for Materials Science (JP)
- University of Cambridge (GB)
- Center for Theoretical Physics (PL)
- University of Bath (GB)
- Arizona State University (US)
- Columbia University (US)
- Politecnico di Milano (IT)
Publication Details
- Journal
- Nano Letters
- Published
- 2025-04-30
- DOI
- https://doi.org/10.1021/acs.nanolett.4c06428
- Citations
- 7
- Primary Topic
- 2D Materials and Applications
- Type
- article
- Field-Weighted Citation Impact
- 3.62
Funders
- U.S. Department of Energy
- Applied Materials
- Basis Foundation
- European Commission
- Ministry of Education, Culture, Sports, Science and Technology
- Vetenskapsrådet
- HORIZON EUROPE Framework Programme
- Optica Foundation
- Engineering and Physical Sciences Research Council
- Japan Society for the Promotion of Science
- H2020 European Research Council
- HORIZON EUROPE Marie Sklodowska-Curie Actions
- HORIZON EUROPE European Innovation Council