Topologically Nontrivial Phase and Phase Transition in Helicenes Induced by Gate Electric Field and Mechanical Strain

Helicenes, characterized by intrinsic chiral geometry and mechanical flexibility, provide a promising organic platform for hosting and manipulating quantum states. By combining tight-binding modeling with topological band theory, we demonstrate that topologically nontrivial phases can emerge in helicenes in the presence of a gate electric field perpendicular to the molecular helix axis, as manifested by topological end states and large gap Chern numbers. In particular, the interplay between the gate electric field and mechanical strain yields rich topological phase diagrams, originating from the intrinsically coupled two-chain structure of helicenes, where the distinct electronic responses of the inner and outer chains to external perturbations lead to intricate gap overlap and band hybridization. Our work establishes helicenes as a versatile class of tunable topological materials with considerable potential for applications in molecular electronics and quantum devices.