Printed High-Entropy Prussian Blue Analogs for Advanced Non-Volatile Memristive Devices

Non-volatile memristors dynamically switch between high (HRS) and low resistance states (LRS) in response to electrical stimuli, essential for electronic memories, neuromorphic computing, and artificial intelligence. High-entropy Prussian blue analogs (HE-PBAs) are promising insertion-type battery materials due to their diverse composition, high structural integrity, and favorable ionic conductivity. This work proposes a non-volatile, bipolar memristor based on HE-PBA. The device, featuring an active layer of HE-PBA sandwiched between Ag and ITO electrodes, is fabricated by inkjet printing and microplotting. The conduction mechanism of the Ag/HE-PBA/ITO device is systematically investigated. The results indicate that the transition between HRS and LRS is driven by an insulating-metallic transition, triggered by extraction/insertion of highly mobile Na⁺ ions upon application of an electric field. The memristor operates through a low-energy process akin to Na⁺ shuttling in Na-ion batteries rather than depending on formation/rupture of Ag filaments. Notably, it showcases promising characteristics, including non-volatility, self-compliance, and forming-free behavior, and further exhibits low operation voltage (V_SET = -0.26 V, V_RESET = 0.36 V), low power consumption (P_SET = 26 µW, P_RESET = 8.0 µW), and a high R_OFF/R_ON ratio of 10⁴. This underscores the potential of high-entropy insertion materials for developing printed memristors with distinct operation mechanisms.