Strain-mediated phase transitions in ZnS-based graphenylene-like nanosheets: a DFTB+ simulation study

Abstract Two-dimensional zinc sulfide (ZnS) nanosheets hold significant promise for next-generation flexible optoelectronics and nano-devices, yet the potential of graphenylene-derived porous architectures and their strain-driven structural dynamics remains unexplored. Motivated by this gap, we employ density-functional tight-binding simulations to investigate novel ZnS nanosheet phases inspired by graphenylene-like (G-like) and the GME nanoporous crystal. We demonstrate the stabilization of both a planar bilayer G-like phase (G-2) and a metastable monolayer cage-like GME phase (GME-1) from the same atomic structure, governed by distinct lattice parameter ranges. Crucially, we identify and characterize reversible, strain-mediated phase transitions between these morphologies, which occur under a biaxial tensile strain of 6.5%–7% (corresponding to a lattice parameter range of 10.30–10.35 Å) relative to the GME-1 equilibrium structure. This transition, enabled by a minimal energy barrier of ∼0.1 eV/ZnS, induces a substantial bandgap modulation of ∼1 eV, directly coupling mechanical deformation to electronic restructuring. Both phases exhibit robust dynamical, thermal (≤500 K), and mechanical stability. This discovery of morphology-dependent stability and reversible, strain-tunable phase transitions with coupled electronic properties in porous ZnS nanosheets paves the way for their application in advanced optomechanical switches, nanosensors, UV photodetectors, and mechanical metamaterials.