Enhancement of electronic and optoelectronic performance of multilayer InSe via strain engineering

In this letter, we report a study on the strain-tuned optical bandgap, piezoresistive effect and photoresponse of multilayer β-InSe. A redshift of photoluminescence is observed in multilayer InSe under uniaxial tensile strains and the shift rate of the optical gap is 57.7 meV/%. The multilayer InSe shows pronounced piezoresistive effect with a reduced resistance and the calculated gauge factor is 47, which is larger than those of graphene and traditional metal foils. The photoresponsivity of the photodetector is enhanced to 115.9 AW^-1 measured at 1.06% uniaxial tensile strain, three times higher than that of a device measured without strain. Our results demonstrate that strain-engineering can effectively modulate electronic and optoelectronic properties of multilayer InSe, opening a door for InSe applications in strain sensors, flexible photodetectors and electronic skin devices.