Combined resistive switching memory and multi-state operation in terpyridine-based Pd(ii) and Fe(iii) complexes for neuromorphic applications

Abstract

Molecular electronic devices with tunable resistance hold significant potential as candidates for next-generation non-volatile memory technology and neuromorphic computation. By introducing subtle modifications to molecular structures and electronic properties, memory performance can be effectively enhanced through optimized molecular design and intra/intermolecular interactions. Coordination compound-based resistive memory devices present a low-cost, solution-processable alternative that could align with industrial demands. In this study, we demonstrate that by carefully designing and synthesizing a tosylated terpyridine molecule, along with its related tos-tpy-Pd(II) (cationic and diamagnetic) and tos-tpy-Fe(III) (neutral and paramagnetic) complexes, they can be utilized for memory and neuromorphic applications. Notably, these complexes exhibit robust responses to electric fields, enabling their operation in low-energy neuromorphic applications. The devices achieved stable memory states (∼500 cycles) and demonstrated multistate operation (∼1000 cycles). Furthermore, extremely stable synaptic plasticity with a high MNIST handwritten number pattern recognition accuracy of ∼80–84% is achieved through the implementation of artificial neural network (ANN) simulations.