Photo-induced oxygen vacancy modulation in solution-processed TiO2/ZnFe2O4 heterointerface for all-oxide dual-mode neuromorphic logic memory

Memristors, with their ability to switch between resistance states and emulate synaptic plasticity, are promising candidates for brain-inspired neuromorphic computing, having the potential to meet the growing demand for energy-efficient, parallel information processing. However, conventional devices are restricted to either electrical or optical operation, limiting multimodal functionality, commonly observed in the nervous systems. Here, we prepared a spin-coated TiO2/ZnFe2O4 heterojunction that effectively mimics synaptic plasticity under electrical and optical stimuli simultaneously, enabling our device to perform configurable logic operations. Ultraviolet photoelectron spectroscopy combined with the X-ray photoelectron spectroscopy studies before and after illumination suggest light-driven oxygen-vacancy modulation dominates the tunneling current through the heterointerface, resulting in persistent photo-response and optical synaptic plasticity. However, the confined filament formation at the heterointerfaces enables plasticity with electrical pulses. Our solution-processed all-oxide heterojunction memristor with multimodal functionality may provide a biologically realistic pathway to a cost-effective, stable alternative in emulating the human brain.