Structure and Spectroscopic Characterisation of Phenanthroline‐Based Iodobismuthate(III) Complexes Utilised for Raw Acoustic Signal Classification

Memristors are promising candidates for neuromorphic systems due to their ability to mimic synaptic behaviour, which is a key feature for the combination of memory and information processing in a single device. In this study, we report the synthesis and characterisation of a series of phenanthroline‐based iodobismuthate(III) complexes with varying cations, such as tetrabutylammonium, tetramethylammonium, and trimethylsulfonium. We have investigated the influence of steric effects on the optical and electrical properties of the compounds. Sandwiched thin layers as memristive devices show analogue, voltage‐dependent potentiation and depression, supporting their synaptic functionality. Along with the decrease in the cation size, the homogeneity of the thin layers on the ITO/glasses and stability of the device were improved. It is noteworthy that devices implemented as a time‐delayed reservoir in the circuit are capable of raw signal classification, successfully classifying environmental signals without any pre‐ or post‐processing steps. These findings advance the design of functional materials for real‐time hardware‐level signal classification, marking a step towards integrated neuromorphic architectures.