Photoexcitation Dynamics and Long‐Lived Excitons in Strain‐Engineered Transition Metal Dichalcogenides

• DOI: 10.1002/adma.202110568
• Publication Date: 2022-03-31T06:34:46Z
• Authors: Navendu Mondal; Nurul Azam; Yuri N. Gartstein; Masoud Mahjouri‐S...; Anton V. Malko
• Keywords: Picosecond; Photoexcitation; Nanosecond; Strain (injury)

Strain-engineering in 2D transition metal dichalcogenide (TMD) semiconductors has garnered intense research interest tailoring the optical properties via strain-induced modifications of electronic bands TMDs, while its impact on exciton dynamics remains less understood. To address this, an extensive study transient absorption (TA) both W- and Mo-based single-crystalline monolayer TMDs grown by a recently developed laser-assisted evaporation method is performed. All spectral features monolayers as fused silica substrates exhibit appreciable redshifts relating to existence strain due growth conditions. Moreover, these systems dramatic slowing down (100s picoseconds few nanoseconds) with increase carrier densities, which strongly contrasts their freestanding form well comparison more traditionally TMDs. The observations are related expected from associated population intervalley dark excitons that can now interplay intravalley excitations. These findings consistent across Mo- W-based TMD families, providing key information about influence conditions nature excitations fostering emerging optoelectronic applications