Strain engineering the properties of graphene and other two-dimensional crystals.

Graphene has been widely studied for its many extraordinary properties, and other two-dimensional layered materials are now gaining increased interest. These excellent properties make thin layer materials very attractive for integration into a wide variety of technologies, particularly in flexible optoelectronic devices. Therefore, gaining control over these properties will allow for a more focused design and optimisation of these possible technologies. Through the application of mechanical strain it is possible to alter the electronic structures of two-dimensional crystals, such as graphene and transition metal dichalcogenides (e.g. MoS2), and these changes in electronic structure can alter their behaviour. In this perspective we discuss recent advances in the strain engineering of thin layer materials, with a focus on using Raman spectroscopy and electrical transport to investigate the effect of strain as well as the effect of strain on the chemical functionalisation of graphene.