Ferroelectric polarization modulated optoelectronic synapses based on BaTiO3/TiO2 heterojunction for non-volatile visual memory

Abstract

The growing demand for neuromorphic computing architectures that mimic biological information processing has driven extensive research on optoelectronic synapses with multimodal neuromodulation capabilities. In this study, BaTiO₃/TiO₂ optoelectronic synaptic devices with high non-volatile memory characteristics were constructed by interfacial energy band engineering. This heterojunction synaptic device achieves a 1350 % enhancement in relaxation time (τ₂ = 84.14 s) compared to conventional BaTiO₃ device (τ₂ = 6.21 s). Moreover, short-term to long-term memory conversion and the cognitive process of “learning experience” are achieved by adjusting light pulse parameters. Through further investigation, a synergistic ferroelectric polarization strategy is proposed, demonstrating that downward polarization extends τ₂ to 202.93 s, with image retention time exceeding 4800 s. The synaptic device demonstrates biological-level energy efficiency (10.45 fJ) while achieving 97.5 % and 89.05 % recognition accuracy on MNIST and Fashion-MNIST datasets, respectively, through convolutional neural networks. This work not only exhibits the application prospect of ferroelectric semiconductor-based heterojunction in artificial optoelectronic synapse but also provides new ideas for the design and application of multimodal neuromorphic devices.