Strain induced bang-gap engineering in layered TiS₃

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By combining ab initio calculations and experiments we demonstrate how the band gap of the transition metal tri-chalcogenide TiS₃ can be modified by inducing tensile or compressive strain. We show by numerical calculations that the electronic band gap of layered TiS₃ can be modified for monolayer, bilayer and bulk material by inducing either hydrostatic pressure or strain. In addition, we find that the monolayer and bilayer exhibits a transition from a direct to indirect gap when the strain is increased in the direction of easy transport. The ability to control the band gap and its nature can have an impact in the use of TiS₃ for optical applications. We verify our prediction via optical absorption experiments that present a band gap increase of up to 10% upon tensile stress application along the easy transport direction.