Fig. 3: Analyzing exciton dynamics of flat and wrinkled WSe₂ depending on the localized strain.

Time-resolved PL from flat WSe₂ (a) and wrinkled WSe₂ at apex (b) and valley (c). d Decay time constants, fitted with bi-exponential or tri-exponential equation, for flat WSe₂ and wrinkled WSe₂ at apex and valley of (a–c). e Schematic illustration of funneling of bright excitons from valley to apex owing to strain-induced energy gradient in real space. CBM and VBM indicate conduction band minimum and valence band maximum, respectively. f Schematic of generation of dark exciton at valley and its conversion to bright exciton at apex owing to different energy level of KK and KQ states under tensile and compressive strain. Simulated maps of steady-state PL emission (g), flux density (h), and bright/dark exciton conversion (i) for valley pumping (top) and apex pumping (bottom). Scale bars are 1 μm.