Lattice Disorder in CuI Enables Filament‐Free Transparent Memristors

Abstract

ABSTRACT The realization of invisible neuromorphic electronics hinges on transparent memories that reconcile high optical transparency with stable analog tunability, which is a challenge unmet by conventional filamentary devices. Here, we introduce an alloyed Cu 1‐ x Ag x I halide transparent semiconductor with dual ionic‐electronic character, which enables a filament‐free switching platform. Ag + incorporation induces lattice distortions within the γ‐phase CuI matrix, expanding interstitial channels and lowering the migration barrier without phase transition. This activates room‐temperature ion migration to dynamically modulate the p‐type hole conductance. Asymmetric electrodes induce spatially distributed ion migration and interfacial modulation, avoiding localized metallic percolation. In situ TEM and EDS mapping confirm reversible Cu + /Ag + redistribution without continuous conductive pathways. Pt/Cu 1‐ x Ag x I/Ag devices exhibit > 80% transparency, low‐voltage readout, and > 2‐year retention. They emulate synaptic plasticity and achieve high‐accuracy handwritten digit recognition. Our findings establish a design strategy for transparent memristors, enabling reliable neuromorphic hardware via ionically mediated electronic transport.