Modulation on the electronic properties and band gap of layered ReSe₂ via strain engineering

Two-dimensional (2D) materials have drawn tremendous attention due to their planar nature, good mechanical, optical and electrical properties especially for flexible electronic devices whose performance could be modulated by external mechanical strains. Here, the piezoresistive property of layered ReSe₂ upon various homogeneous strains is investigated. Highly sensitive and reliable response in resistance has been observed for ReSe₂-based flexible devices under tensile/compressive strains. Photoluminescence spectra measurement further confirmed the strain modulation on the band gap energy, leading to the piezoresistive property in ReSe₂. Additionally, it is found that the electromechanical behavior of ReSe₂ can be greatly influenced by the directions of applied strains, where the gauge factor is 4.29 times higher when the strain is applied along the b-axis than that obtained under strain perpendicular to b-axis. The strain-direction-sensitive electromechanical behavior can be attributed to the different band gap change induced by strains along various directions. These results can contribute to the design, performance improvement and application development of flexible electronic devices based on anisotropic 2D materials.