Chloride Ion Vacancy-Mediated Multilevel Bipolar Resistive Switching in Lead-Free All-Inorganic Halide Perovskite Thin Films

Halide perovskites have attracted considerable interest for resistive switching (RS) applications due to their high ionic conductivity, defect-tolerant structures, and ability to support fast ion migration, making them promising for nonvolatile memory and neuromorphic computing. However, most inorganic halide perovskites contain hazardous lead, raising environmental concerns, while mixed-halide compositions suffer from phase segregation and instability. In this study, we report potassium trichloridocuprate (II) (KCuCl3) as a novel lead-free, all-inorganic halide perovskite (LFAIHP) for RS applications. The W/KCuCl3/FTO memristors exhibit multilevel RS, superior endurance, and highly stable resistance states over a prolonged time. This study suggests that the manifestation of chloride ion vacancies in the as-synthesized KCuCl3 layer and the reversible migration of Cl– ions under an applied electric field lead to its filamentary switching characteristics. The results demonstrate that nonstoichiometric KCuCl3 can pave the way toward developing lead-free halide perovskite-based low-power, reliable, environmentally friendly, nonvolatile memory and neuromorphic computing devices.