Large strain tunability of excitons in ZrSe₃ via cryogenic environment

Strain engineering provides an efficient approach for tailoring the electronic and optical properties of two-dimensional (2D) materials, making them suitable candidates for straintronic applications, especially flexible optoelectronic devices. Therefore, the larger strain response on bandgap of 2D materials is highly on demand. Here, we systematically investigated the change of bandgap of multilayer IV–V transition metal trichalcogenide ZrSe₃, which is transferred onto flexible polycarbonate substrates, through the differential reflectance spectroscopy. A pronounced redshift of excitonic peak is observed with the applied biaxial compressive strain on multilayer ZrSe₃ through cryogenic cooling. A gauge factor of ~ 136 meV/%, which is the featured parameter related to strain response, is obtained. This value is comparable with the highest strain response reported among 2D materials to date. The exceptional strain tunability highlights ZrSe₃ as a promising material for flexible photodetectors and provides new insights into the manipulation of optical properties in 2D materials.