Probing the Formation of Dark Interlayer Excitons via Ultrafast Photocurrent.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 37788809.
- Also identified by DOI 10.1021/acs.nanolett.3c01708 and PMC identifier 10603811.
- 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
Optically dark excitons determine a wide range of properties of photoexcited semiconductors yet are hard to access via conventional time-resolved spectroscopies. Here, we develop a time-resolved ultrafast photocurrent technique (trPC) to probe the formation dynamics of optically dark excitons. The nonlinear nature of the trPC makes it particularly sensitive to the formation of excitons occurring at the femtosecond time scale after the excitation. As a proof of principle, we extract the interlayer exciton formation time of 0.4 ps at 160 μJ/cm<sup>2</sup> fluence in a MoS<sub>2</sub>/MoSe<sub>2</sub> heterostructure and show that this time decreases with fluence. In addition, our approach provides access to the dynamics of carriers and their interlayer transport. Overall, our work establishes trPC as a technique to study dark excitons in various systems that are hard to probe by other approaches.