Nanoscale Resistive Switching in Electrodeposited MOF Prussian Blue Analogs Driven by K-Ion Intercalation Probed by C-AFM

Abstract

K-ion intercalation in Prussian blue analogues (PBAs) is a well-established charge storage mechanism in potassium-ion batteries; here, we demonstrate that this process also responsible for nanoscale resistive switching in PBA-based material. Using conductive atomic force microscopy (C-AFM), we directly visualize and electrically control reversible conductance modulation within sub-100 nm volumes, linking localized K+ redistribution to Fe2+/Fe3+ redox reconfiguration. The switching is polarity-selective, with Prussian white (PW) and Prussian blue (PB) both exhibiting unidirectional resistive switching (URS) at opposite bias polarities, consistent with oxidation- and reduction-driven transport, respectively. These processes are governed by electrically confined ion−electron coupling, where K-ion motion modulates small-polaron hopping within the PBA framework. The switching dynamics are strongly dependent on ionic mobility, with PW sustaining operation up to 200 V/s and PB up to 50 V/s, highlighting the critical role of K-ion concentration in enabling fast redox kinetics. This nanoscale switching mechanism, combined with spatial confinement below 100 nm, enables high-density device integration without interference between them. Moreover, PBAs provide a chemically versatile, earth-abundant platform with tunable ionic and electronic properties, fabricated via a single-step, aqueous, room-temperature process compatible with CMOS technology. This solution-processable approach enables low-temperature fabrication, scalability to large-area substrates, and integration into diverse device architectures. The use of simple salt precursors ensures low-cost manufacturing, while environmentally friendly synthesis and nontoxic, noncontaminating disposal enhance overall sustainability.