BiFeO₃‑Based Flexible Ferroelectric Memristors for Neuromorphic Pattern Recognition

Flexible ferroelectric devices have been a hot-spot topic because of their potential wearable applications as nonvolatile memories and sensors. Here, high-quality (111)-oriented BiFeO₃ ferroelectric films are grown on flexible mica substrates through an appropriate design of SrRuO₃/BaTiO₃ double buffer layers. BiFeO₃ exhibits the largest polarization (saturated polarization P_s ≈ 100 μC/cm², remnant polarization P_r ≈ 97 μC/cm²) among all the reported flexible ferroelectric films, and ferroelectric polarization is very stable in 10⁴ bending cycles under 5 mm radius. Accordingly, the ferroelectric memristor behaviors are demonstrated with continuously tunable resistances, and thus, the functionality of spike-timing-dependent plasticity is achieved, indicating the capability of flexible BiFeO₃-based memristors as solid synaptic devices. Moreover, in artificial neural network simulations based on the experimental characteristics of the memristor, a high recognition accuracy of ∼90% on handwritten digits is obtained through online supervised learning. These results highlight the potential wearable applications of flexible ferroelectric memristors for data storage and computing.