Regulating Memristor Performance of Organic-Inorganic Hybrid Polyoxometalates via Counter Cations

Abstract

Tailoring the performance of memory devices through molecular-level engineering of active materials represents a promising strategy for developing high-performance memory. In this study, we synthesized two polyoxometalate (POM), (Ph4P)6(Cu2I2)(MnMo6O18L2)2 (1) and H2(n-HTTP)4(Cu2I2)(MnMo6O18L2)·2CH3CN (2) (L = 2-(hydroxymethyl)-2-(pyridine-4-yl)-1,3-propanediol, n-HTTP=n-hexyltriphenylphosphonium), by reacting the precursor (TBA)3MnMo6O18(L)2·2CH3CN with Ph4P⁺and n-HTTP⁺, respectively. Both ITO/1/Ag and ITO/2/Ag devices exhibited similar resistive switching behaviour. At room temperature, ITO/1/Ag demonstrated a superior ON/OFF ratio (2.88 × 104) compared to ITO/2/Ag (1.01× 103). Remarkably, ITO/1/Ag and ITO/2/Ag also maintained excellent switching performance at high temperatures. Molecular-level analysis reveals that Compound 1 possesses a smaller interlayer spacing, which facilitates electron transfer. Conductivity tests demonstrate that the conductivity of 1 is higher than that of 2. This work illustrates that modulating memristor characteristics through rational selection of counter cations is an effective approach toward achieving high performance memory devices.