Fig. 3: Self-powered 2D ferro-ionic conduction via spatial flexoelectric nano-manipulation.

a Ferro-ionic phase transition mechanism in the 2D α-In₂Se₃/CuInP₂S₆ heterostructure, which indicates the flexoelectric energy storage. b Cross-sectional TEM image and its corresponding SAED pattern of the bent In₂Se₃ lattice structure, which induces the nanoscale flexoelectricity. c PFM amplitude hysteresis behavior with nanoscale mechanical bending, indicating the conduction threshold reduction. Self-powered system in 2D ferro-ionic conduction, which was experimentally verified with d semi-log I–V curve, e I_max distribution, and f ratio of I_{max, with strain} to I_{max, without strain}. g Spatial I_max mapping in free-standing 2D α-In₂Se₃/CuInP₂S₆ heterostructure, which enables the sub-50 nm flexoelectric manipulation.