R&D: Molecular-Potential and Redox Coregulated Cathodic Electrosynthesis toward Ionic Azulene-Based Thin Films for Organic Memristors

ACS Applied Materials & Interfaces has published an article written by Qiongshan Zhang, Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China, Dongchuang Wu, School of Energy and Power Engineering, North University of China, Taiyuan 030051, China, Yubin Fu, Center for Advancing Electronics Dresden (cfaed) & Department of Chemistry and Food Chemistry, Technische Universität Dresden, Dresden 01062, Germany, Jinyong Li, Yu Chen, and Bin Zhang, Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China.

Abstract: “Organic memristors as promising electronic units are attracting significant attention owing to their simplicity of molecular structure design. However, fabricating high-quality organic films via novel synthetic technologies and exploring unprecedented chemical structures to achieve excellent memory performance in organic memristor devices are highly challenging. In this work, we report a cathodic electropolymerization to synthesize an ionic azulene-based memristive film (PPMAz-Py⁺Br^–) under the molecular-potential and redox coregulation. During the cathodic electropolymerization process, electropositive pyridinium salts migrate to the cathode under an electric field, undergo a reduction-coupling deprotonation reaction, and polymerize into a uniform film with a controllable thickness on the electrode surface. The prepared Al/PPMAz-Py⁺Br^–/ITO devices not only exhibit a high ON/OFF ratio of 1.8 × 10³, high stability, long memory retention, and endurance under a wide range of voltage scans, but also achieve excellent multilevel storage and history-dependent memristive performance. In addition, the devices can mimic important biosynaptic functions, such as learning/forgetting function, synaptic enhancement/inhibition, paired-pulse facilitation/depression, and spiking-rate-dependent plasticity. The tunable memristive performances are attributed to the capture of free electrons on pyridinium cations, the migration of the aluminum ions (Al³⁺), and the form of Al conductive filaments under voltage scans.“