Phase-dependent memristive behaviors in FAPbI3-based memristors

Abstract

In this paper, memristors with a structure of Ag/FAPbI3/FTO were fabricated by using FAPbI3 perovskite as the active layer. The FAPbI3 films were synthesized with a solution-based method and different annealing temperatures resulted in different phases, i.e., δ-phase and α-phase. The devices based on FAPbI3 films with these two phases were characterized by voltage sweeps with different ranges and polarity. It was found that devices based on δ-FAPbI3 films resulted from annealing at 80 °C exhibited good memristive behaviors, i.e., the device resistance (in terms of current) changes continuously according to the charge flowing through the device. In particular, under the stimulation of positive voltage sweeps, the device current gradually increased, and in contrast, negative voltages reduced the current accordingly with the number of applied sweeps. The device response in terms of changes in current showed good consistency with the number of applied voltage sweeps, even for situations with combination of positive and negative voltage sweeps. It was further found that relatively large voltages with a threshold of ~0.4 V can be used to induce memristive response in δ-FAPbI3 based devices. The memristive effect is related to Ag electrodes, which are expected to gradually form bridge-like conductive filaments (CFs) between top and bottom electrodes. The repeated positive voltages applied to device induce gradual formation of CFs while negative voltages tend to disrupt CFs also in a gradual manner. As a result, memristive behavior was realized in Ag/δ-FAPbI3/FTO structured memristors, which can be used for neuromorphic device applications (e.g., electronic synapses).