Flexible Pyrene/Phenanthro[9,10‐d]imidazole‐Based Memristive Devices for Mimicking Synaptic Plasticity

Abstract

Emulation of memory and learning functionalities of biological synapses using a two‐terminal electronic device with bidirectional progressive conductance modulation is an indispensable move toward the development of bio‐inspired neuromorphic networks. Herein, a small molecule 1‐phenyl‐2‐(4‐(pyren‐1‐yl)phenyl)‐1H‐phenanthro[9,10‐d]imidazole (pPPI) is synthesized, and an organic synaptic device is investigated with bipolar resistive switching characteristics and bidirectional gradual conductance regulation for the first time. A facile solution‐processing approach can be used to deposit a uniform active layer on flexible substrates. Our pPPI‐based nonvolatile memory presents a superior electrical performance, such as relatively stable and reproducible bipolar resistive switching phenomena and a robust data retention capability. In particular, our device displays a remarkably large switching window of around 7.0 × 107, which is a record ON/OFF ratio compared with other small molecule‐based memories up to now. In addition, comprehensive cognitive functions of chemical synapses, for example, the excitatory postsynaptic current (EPSC), paired‐pulse facilitation/depression (PPF/PPD), spike‐rate‐dependent plasticity (SRDP), and spike‐time‐dependent plasticity (STDP) are successfully achieved. Our achievement of a synaptic device based on small molecules may boost the development of bio‐inspired neuromorphic systems using organic electronics.