2025/01/02 by R. S. Saraswat, Saraswat, Rishabh, Rekha Verma +3 · 1 citation
Engineering · Materials Science · Physics and Astronomy · #2D Materials and Applications #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Perovskite Materials and Applications #Semiconductor Quantum Structures and Devices
paper · pdf · doi:10.48550/arxiv.2501.01410
openalex publication_date 2025/01/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Phonon-assisted photoluminescence (PL) in molybdenum-based two-dimensional dichalcogenides is typically weak due to the dormant phonon coupling with optically inactive momentum-dark (intervalley) excitons, unlike in tungsten-based dichalcogenides where such processes are more prominent. Despite this inefficiency, we revisit excitons in MoS2 using rigorous finite-momentum Bethe-Salpeter equation calculations to identify ways to enhance phonon-assisted recombination channels. Our ab-initio results, complemented by group-theoretic analyses, reveal that while unstrained MoS2 exhibits no phonon-assisted PL emissions at cryogenic temperatures due to forbidden A′′ phonon modes, biaxial strain opens a pathway to significantly intensify this emission by activating hole-phonon A′-mediated scattering channels. By calculating allowed exciton-phonon matrix elements and scattering rates, we demonstrate how strain redistributes oscillator strengths toward radiative recombination. These findings provide a promising route to improving PL emission efficiency in various metal dichalcogenide monolayers through strain engineering and offer valuable insights for further exploration of exciton-phonon dynamics, including time-resolved spectroscopic studies.