With the aim of addressing the growing challenge of approaching the end of Moore's law and von Neumann bottleneck, the evolution of neuromorphic computing based on memristors that emulate the behaviors of the brain has attracted great attention. Organic-inorganic hybrid lead halide perovskites with inherent hybrid ionic-electronic conduction ability have been proposed as promising candidates for memristors to replace traditional charge-based memory. Here we propose MA 0.85 Cs 0.15 PbI 3 memristors with high surface crystallinity and stable operation in the atmospheric environment by mixing inorganic cation Cs + and organic cation MA + . The prepared memristors present excellent resistive switching performances including low operation voltage, high ON/OFF ratio, stable endurance, long retention, and robustness under ambient condition. Besides that, four distinct resistance states have been obtained in the above devices by modifying the operation voltages. Moreover, the resistance switching processes can be controlled both by electrical field and light illumination. Finally, this research provides utilization potentiality in the optical and electrical two-dimension controlled multilevel information devices with a total of five stable resistance states. The present work would offer an effective way to develop multifunctional high-density data-storage applications by storing multiple resistance states in a single unit cell.
Yang Feng,Xu Gao,Ya-Nan Zhong,Jia-Ling Wu,Jian-Long Xu,Sui-Dong Wang
Emerging organic synaptic devices are promising in exploring soft and biocompatible neuromorphic computing systems. By means of a simple and low-cost solution process, the polymer thin-film memristors are designed and characterized. The polymer memristors have a bilayer structure composed of an ion-rich semiconducting layer and an ion-collecting conducting layer, where the ion redistribution depending on device operation history has an impact on carrier concentration and results in the memristive characteristics. A visible electrochromic feature is observed during the electrical measurements, supporting the proposed Li + ion drift/diffusion mechanism. The polymer memristors show the continuous and reversible conductivity tuning with a temporary memory effect, which enables the successful emulation of the frequency-dependent synaptic plasticity. The polymer thin-film memristors may offer a strategy for developing building blocks of organic neuromorphic circuits.
Lu Han,Dehui Wang,Mengdie Li,Yang Zhong,Kanghong Liao,Yingbo Shi,Wenjing Jie
As the development of neuromorphic computing , it is meaningful to explore the synaptic memristors based on organic materials owing to their advantages in low cost, good mechanical flexibility and strong biocompatibility. In this work, organic pentacene thin films have been deposited on different substrates by the thermal evaporation method. The prepared thin films on SiO 2 /Si substrates demonstrate the co-existence of digital and analog resistive switching (RS) behaviors as well as a series of synaptic plasticity. To characterize the flexibility of the organic thin films, lateral memristors have been fabricated on polyethylene terephthalate (PET) substrates and demonstrate comparable RS behaviors when the bending radius is decreased to 1.26 cm or after 1000 bending. Furthermore, vertical memristors with Pt/pentacene/indium tin oxide (ITO) structure have been constructed when the organic thin films are deposited on ITO/PET substrates, exhibiting bipolar RS behaviors with low SET voltage of 0.65 V. The vertical synaptic memristors can be used to simulate the “learning-forgetting” experience of human brain. More importantly, an artificial neural network (ANN) can be simulated based on the vertical synaptic memristors, demonstrating 93.8 % recognition accuracy for hand-written digit image. This study suggests potential applications of the organic pentacene thin films for neuromorphic computing.