Spectral properties of the dynamic state transition in metal halide perovskite-based memristor exhibiting negative capacitance

The evolution of device properties in memristor switching between high- and low-resistance states is critical for applications and is still highly subjected to significant ambiguity. Here, we present the dynamic state transition in a 2D Ruddlesden–Popper perovskite-based memristor device, measured via impedance spectroscopy. The spectral evolution of the transition exhibits a significant transformation of the low frequency arc to a negative capacitance arc, further decreasing the device resistance. The capacitance–frequency evolution of the device indicates that the appearance of the negative capacitance is intimately related to a slow kinetic phenomenon due to ionic migration and redistribution occurring at the perovskite/metal contact interface. In contrast, no negative capacitance arc is observed during the state transition of a memristor device where the contact is passivated by an undoped Spiro-OMeTAD interfacial layer. The switching mechanisms are entirely different, one due to interface transformation and the other due to filamentary formation.