Dual Action Spectroscopy Exposes the Bright and Dark Excitons of Room-Temperature WSe<sub>2</sub>
While it has long been accepted that the role of momentum dark excitons in the photoresponse of transition metal dichalcogenides (TMDs) is critical, their weak optical signature inhibits their study through conventional means. Here we expose the room-temperature contributions of both bright and dark excitons to the behavior of a TMD, WSe<sub>2</sub>, from monolayer to multilayer to bulk. To do so, we present dual action spectroscopy, a photocurrent- and luminescence-detected Fourier-transform excitation spectroscopy scheme, to microscopically map the energy landscape of WSe<sub>2</sub>. While bright excitons naturally dominate the luminescence response of the material, dark excitons dominate the current response. Notably, the dark <b>KK'</b> exciton is more accessible than the ground state <b>KΛ</b>, while current maps reveal a disparity in the diffusivity of the two states. This work provides the basis for a new, current-detected approach to study the dynamics of dark exciton states across different materials.
Authors
- Karuppasamy Soundarapandian (ORCID: https://orcid.org/0000-0002-9664-9095)
- Frank H. L. Koppens (ORCID: https://orcid.org/0000-0001-9764-6120)
- L Donati
- Sefaattin Tongay (ORCID: https://orcid.org/0000-0001-8294-984X)
- Riccardo Bertini (ORCID: https://orcid.org/0000-0001-7225-0277)
- Takashi Taniguchi (ORCID: https://orcid.org/0000-0002-1467-3105)
- Kenji Watanabe (ORCID: https://orcid.org/0000-0003-3701-8119)
- Luca Bolzonello (ORCID: https://orcid.org/0000-0003-0893-5743)
- J. L. Wragg
- N.F. van Hulst (ORCID: https://orcid.org/0000-0003-4630-1776)
Institutions
- Institució Catalana de Recerca i Estudis Avançats (ES)
- Institute of Photonic Sciences (ES)
- National Institute for Materials Science (JP)
- Shanghai Institute for Science of Science (CN)
- Centre Hospitalier de Lens (FR)
- European Theoretical Spectroscopy Facility (BE)
- Barcelona Institute of Science and Technology (ES)
- Institute of Science and Technology
- Arizona State University (US)
Publication Details
- Journal
- Nano Letters
- Published
- 2025-04-04
- DOI
- https://doi.org/10.1021/acs.nanolett.4c06349
- Citations
- 4
- Primary Topic
- 2D Materials and Applications
- Type
- article
- Field-Weighted Citation Impact
- 2.07
Funders
- Fundación Cellex
- Ministerio de Ciencia, Innovación y Universidades
- Generalitat de Catalunya
- FUNDACIÓ Privada MIR-PUIG
- European Research Council