Photostriction-driven phase transition in layered chiral NbOX2 crystals: electrical-field-controlled enantiomer selectivity

Abstract The physical properties of chiral crystals are inherently tied to their structural handedness, making external control of chirality a key challenge for functional materials design. However, the ability to select between structural enantiomers remains challenging, both theoretically and experimentally. In this work, we demonstrate a two-step pathway for enantiomer selectivity in layered chiral NbOX 2 (X = Cl, Br, I) crystals based on photostriction-driven phase transitions. Ab-initio simulations reveal that optical excitation is capable of inducing a structural phase transition in NbOX 2 from the monoclinic ( C 2) ground state to the higher-symmetry ( C 2/ m ) structure. In the resulting transient high-symmetry state, an applied electric field breaks the residual inversion-symmetry degeneracy, selectively stabilizing one enantiomeric final state configuration over the other. Our results establish a combined optical-electrical control scheme for chiral materials, enabling reversible and non-contact enantiomer selection with potential applications in ultrafast switching, optoelectronics, and chiral information storage.