Tuneable Optoelectronic Response In Flexible PtSe₂ Films

Noble metal dichalcogenides such as platinum diselenide (PtSe₂) belong to the material class of layered 2D materials. Some of these materials exhibit a transition from a direct bandgap semiconductor to a semi-metal as the layer thickness increases and have been shown to possess type-II Dirac semi-metallic behavior along with topological surface states [1]. Furthermore, the occurrence of polarization sensitive optoelectronic response indicates an inherent symmetry breaking in this material, which nominally crystallizes in the isotropic hexagonal 1T phase [2]. This study investigates PtSe₂ polycrystalline films on a platform that enables to apply controlled strain. Specifically, the low temperature thermally assisted conversion (TAC) of platinum allows to grow the films directly on flexible substrates. Polarization dependent measurements reveal characteristics of a second-order nonlinear response that can be tuned under mechanical deformation. This work provides insights into the origin of anisotropic optoelectronic response in PtSe₂ and introduces a control parameter for actively modulating its response to polarized light, with potential applications in flexible optoelectronics.

[1] Y. Wang et al., Nano Lett. 15, 4013 (2015).

[2] M.Hemmat et al., arXiv:2304.02070 (2023).