Achieving Giant Linear Optical Response Tunability in Monolayer GeSe for Advanced Strain Sensor Applications

Two-dimensional (2D) layered nanomaterials with exceptional flexibility offer a promising platform for the development of advanced microstrain sensors. Herein, we meticulously examined the linear optical response of monolayer GeSe subjected to a spectrum of strains, spanning from −3 to 3%, encompassing both uniaxial and biaxial strain configurations, to uncover the strain-sensing capabilities of monolayer GeSe. Focusing on the perspective of the energy difference between the conduction and valence bands at high-symmetry points, we observed a significant strain-induced variation in transition energy, with sensitivities reaching up to 152.14 meV/% under biaxial strain. The transition energies demonstrate a near-perfect linear correlation with the applied strain, highlighting a highly predictable and reliable strain response. This pronounced strain-responsive behavior is attributed to the intricate interplay between orbital overlap and geometric modifications. In the context of light-field coupling with monolayer GeSe, the 1.6 eV absorption peak within the linear optical dispersion spectrum is observed to blueshift with increasing biaxial strain and uniaxial strain along the a -axis, contrastingly redshifting with uniaxial strain along the b -axis. These findings reveal that the magnitude of strain can be discerned by resolving the displacement of the linear optical absorption peaks, thereby laying a robust theoretical foundation for the engineering of monolayer GeSe-based strain sensors.