Voltage‐Programmable Switching in Halide Perovskite Memristors by Asymmetric Contact Engineering

ABSTRACT Metal halide perovskites combine mixed ionic–electronic conduction with low‐temperature processing, yet most perovskite memristors operate in a single mode, either nonvolatile bipolar resistive switching (RS) or volatile threshold switching (TS). This limits in‐device multi‐role reuse and drives peripheral overhead. We introduce a single asymmetric transport layer at one contact that makes bias polarity the mode selector. The built‐in field adds to or opposes the applied field, yielding nonvolatile RS under positive sweeps and volatile TS with self‐reset under negative sweeps in the same device. The approach is process‐compatible across C ₆₀ , NiO _x , and Spiro‐OMeTAD. In C ₆₀ ‐based devices, we further observe improved retention (∼2.0 × 10 ⁴ s), endurance (∼6 × 10 ³ cycles), and storage stability (∼1300 h) vs. symmetric control. Mechanistically, Mott–Schottky analysis reveals a finite built‐in voltage that stabilizes or dissolves halide‐vacancy filaments depending on polarity, explaining the reconfigurability. Functionally, negative pulses realize short‐term, self‐erasing updates, while positive pulses consolidate long‐term weights under a unified read bias—providing an intrinsic stability–plasticity balance. This minimal asymmetry streamlines compute‐in‐memory and neuromorphic systems.