Opportunity of the Lead-Free All-Inorganic Cs₃Cu₂I₅ Perovskite Film for Memristor and Neuromorphic Computing...

Recently, several types of lead halide perovskites have been demonstrated as active layers in resistive switching memory or artificial synaptic devices for neuromorphic computing applications. However, the thermal instability and toxicity of lead halide perovskites severely restricted their further practical applications. Herein, the environmentally friendly and uniform Cs₃Cu₂I₅ perovskite films are introduced to act as the active layer in the Ag/Cs₃Cu₂I₅/ITO memristor. Generally, the Ag ions could react with iodide ions and form AgI compounds easily, so the Ag/PMMA/Cs₃Cu₂I₅/ITO memristor was designed by employing the ultrathin polymethylmethacrylate (PMMA) layer to avoid the direct contact between the top Ag electrode and Cs₃Cu₂I₅ perovskite films. After optimization, the obtained memristor demonstrated bipolar resistive switching with low operating voltage (< ±1 V), large on/off ratio (10²), stable endurance (100 cycles), and long retention (>10⁴ s). Additionally, biological synaptic behaviors including long-term potentiation and long-term depression have been investigated. By using the MNIST handwritten recognition data set, the handwritten recognition rate based on experimental data could reach 94%. In conclusion, our work provides the opportunity of exploring the novel application for the development of next-generation neuromorphic computing based on lead-free halide perovskites.