Fluorinated 2D Ruddlesden–Popper Perovskite-Based Flexible Memristor for Neuromorphic Application

Metal halide perovskites (MHPs) exhibit high ionic mobility, defect tolerance, tunable composition, and low ion migration energy, making them attractive for nonvolatile memory and artificial synapses. However, 3D MHPs suffer from environmental instability and uncontrolled ion transport. To overcome these challenges, two-dimensional (2D) halide perovskites offer better alternatives owing to their well-controlled phase purity, anisotropic charge transport properties, and enhanced moisture stability. In this study, we employ a pure 2D Ruddlesden–Popper (RP) fluorinated perovskite, 4-fluorobenzylamine lead bromide [(4-FBA)2PbBr4], inspired by large organic cation-based stable 2D perovskites as the active layer in a flexible Ag/(4-FBA)2PbBr4/ITO/PET device structure. This device exhibits stable and reproducible bipolar resistive switching (RS) behavior with a high ON/OFF ratio, good endurance over multiple cycles, and long-term data retention. Furthermore, our flexible memristor device exhibits minimal variation in electrical characteristics under mechanical bending, demonstrating robust mechanical stability. Besides that, the I–V characteristics were thoroughly analyzed to identify the dominant charge transport mechanisms in various voltage regimes. The results reveal distinct conduction processes, providing insights into the physical origin of the resistive switching. Moreover, electrical pulse modulation shows reliable synaptic behaviors, including paired-pulse facilitation (PPF), paired-pulse depression (PPD), long-term potentiation (LTP), and long-term depression (LTD) even under mechanical bending. These characteristics closely emulate essential functions of biological synapses, demonstrating the ability of the system to modulate synaptic weights in response to external stimuli. This work highlights the potential of our 2D halide perovskite for flexible resistive switching memory and neuromorphic applications.