In collaboration with colleagues form Politecnico di Milano we have investigated ultrafast dynamic in strained systems.
We investigated the effects of uniaxial strain on charge carrier dynamics in WS2 monolayers that has to be considered when 2D crystals are to be employed in flexible optoelectronic devices. All decay curves are fitted using a biexponential decay function, convoluted with a Gaussian function. We observed that for uniaxial tensile strain (εp up to 0.6%) slow decay time of the K-K exciton monotonously increase of as function of strain. These results support that exciton dynamics are modulated by the strain dependence of the energy gap, possibly turning the direct band gap into an indirect gap. However, fast decay time constant has not shown some physical meaningful dependence on strain and it has to be further investigated.