Bis(Formazanate) Nickel(II) Complex as a Promising Active Material for Resistive Random Access Memory Device: Impact of the Metal Center on Memory Device Performance

ABSTRACT A mononuclear bis(formazanate) Ni(II) complex 1 , [Ni II L 2 ], with a redox‐active formazan ligand, 1‐(benzothiazol‐2‐yl)‐5‐(2‐benzoyl‐4‐chlorophenyl)‐3‐phenyl, LH, was designed, synthesized, and structurally characterized in detail by numerous characterization techniques, including the single‐crystal x‐ray diffraction (SCXRD) technique. As evidenced by SC‐XRD, complex 1 exists in an octahedral geometry, with the nickel (II) center being surrounded by two tridentate formazanate ligands. The cyclic voltammogram of the Ni(II) complex displays reversible redox events involving both the ligand and the metal center, highlighting the ability of the complex to undergo both oxidation and reduction processes. The [Ni II L 2 ] complex was additionally utilized as the active material to construct a resistive switching memory device, Ag/Ni II L 2 /FTO, which exhibited excellent resistance switching behaviour with a high I ON /I OFF ratio (10 4 ), low switching voltage, and admirable endurance stability (450 cycles) for nonvolatile memory based on emerging materials.