Tailoring the optical properties of 2D transition metal dichalcogenides by strain

Among the ever-growing family of two-dimensional (2D) materials, those with semiconducting properties --chiefly transition metal dichalcogenides, or TMDCs-- are of particular interest for photonic applications, specifically in the field of flexible optoelectronics. Thanks to their peculiar morphology, indeed, 2D materials can be stretched by various means, revealing the ability to withstand remarkably large mechanical deformations (elastic strains of up to 10%). In this work, we review the many striking effects of such deformations on the optical properties of TMDCs and related materials and present novel strategies to induce and control the strain on TMDC layers, which provide the blueprint for the realization of strain-tuneable, flexible photonic devices based on 2D semiconductors.