Effect of strain on exciton dynamics in monolayer WS₂

The exciton dynamics in a WS₂ monolayer with strain are studied by transient absorption measurements. We measure the differential transmission signal from monolayer WS₂ as a function of the probe wavelength at different levels of strain applied to the sample. The differential transmission spectrum has a positive maximum value at about 614 nm and shows no significant strain dependence. By time-resolving the differential transmission signal, we find that the strain has a minimal effect on the exciton formation process. However, the exciton lifetime is significantly reduced by strain. These results provide useful information for applications of WS₂ in flexible electronic and optoelectronic devices where strain is inevitable. (paper)