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 NiO_x/SnO₂p-n heterojunction synaptic memristor based on NiO_xand 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/NiO_x/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.