Fig. 4: Dark and bright exciton navigation across a local strain landscape.
From: Probing dark exciton navigation through a local strain landscape in a WSe2 monolayer
a Time-resolved PL from both the plateauing features and red-shifting features in device D4 reveal lifetimes associated with each set of 5.4 ± 0.2 and 48.2 ± 0.6 ps, respectively. Inset: Close up of the first 30 ps of the time evolution, with the laser pulse shown. The red-shifted features have a ~10 ps delay relative to the plateauing features. b Finite element method modeling of strain in the hBN/WSe2/hBN heterostructure as it is displaced a distance d by the fiber. The top part of the figure corresponds to d = 300 nm (strain of 5%). c Schematic of the strain-induced energy potential due to the fiber facet (dark blue surface). Bright (white spheres) and dark (black spheres) excitons navigate this potential through a combination of diffusion (yellow arrows) and drift (red arrow); only dark excitons have a long enough lifetime to reach the energetic minimum.
