Two-terminal artificial synapse with hybrid organic–inorganic perovskite (CH3NH3)PbI3 and low operating power energy (∼47 fJ/μm2)

Organic–inorganic hybrid perovskite (CH3NH3)PbX3 [X = I−, Cl−, and Br−] materials were evaluated with memristors for resistive switching (RS) and synaptic functionalities. Analog or multilevel memory behaviors, as well as digital RS characteristics of the Ag/MAPbI3/FTO device structure, were observed in the case of CH3NH3PbI3, whereas (CH3NH3)PbCl3 and (CH3NH3)PbBr3 showed no switching characteristics. The conduction mechanism of RS was dominated by ohmic conduction, space-charge-limited conduction (SCLC), and trap-filled SCLC in both the low-resistance state and the high-resistance state. It is considered that the formation of the β-AgI phase at the interface between Ag and MAPbI3 thin films resulted in different RS and synaptic function behaviors. We successfully emulated the fundamental synaptic characteristics with only a Ag/MAPbI3/FTO memristor, such as the spike-rate-dependent plasticity, paired-pulse facilitation, post-tetanic potentiation, transition from short-term memory to long-term memory, and spike-timing dependent plasticity. The energy consumption of the MAPbI3-based memristor was estimated to be as low as 47 fJ/μm2. Our results indicate that organic–inorganic hybrid perovskite (CH3NH3)PbI3 can be adopted in brain-inspired synaptic devices for hardware-based neuromorphic system applications.