Aging-induced nanocrystalline boundary coalescence in solution-process synaptic memristor.

Aging-induced contact enhancement is a prominent natural phenomenon in materials science. However, it has often been overlooked in nanocrystalline films. Herein, we developed a NiOx/SnO2p-n heterojunction synaptic memristor based on NiOxand SnO2nanocrystals inks, where aging-driven nanocrystal boundary coalescence serves as the origin of improved memristive switching and synaptic emulation. SnO2nanocrystals with amorphous surfaces undergo gradually boundary coalescence after film formation to strengthen bonding between nanocrystals. The ITO/NiOx/SnO2/Ag device exhibits enhanced memristive behavior with aging time at room temperature, and thermal treatment accelerates this aging process. The device emulates synaptic functions of long-term potentiation/depression, excitatory/inhibitory postsynaptic current, and short-term/long-term memory. This work elucidates how aging-driven nanocrystalline evolution facilitates the low-cost fabrication of high-performance neuromorphic devices via solution processing and thermal acceleration.