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 polyoxometalates (POMs), (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.