Tunable Intervalence Charge Transfer in Ruthenium Prussian Blue Analog Enables Stable and Efficient Biocompatible Artificial Synapses

摘要

Emerging concepts for neuromorphic computing, bioelectronics, and brain-computerinterfacing inspire new research avenues aimed at understanding the relationshipbetween oxidation state and conductivity in unexplored materials. Thisreport expands the materials playground for neuromorphic devices to include amixed valence inorganic 3D coordination framework, a ruthenium Prussian blueanalog (RuPBA), for flexible and biocompatible artificial synapses that reversiblyswitch conductance by more than four orders of magnitude based on electrochemicallytunable oxidation state. The electrochemically tunable degree ofmixed valency and electronic coupling between N-coordinated Ru sites controlsthe carrier concentration and mobility, as supported by density functional theorycomputations and application of electron transfer theory to in situ spectroscopyof intervalence charge transfer. Retention of programmed states is improvedby nearly two orders of magnitude compared to extensively studied organicpolymers, thus reducing the frequency, complexity, and energy costs associatedwith error correction schemes. This report demonstrates dopamine-mediatedplasticity of RuPBA synapses and biocompatibility of RuPBA with neuronal cells,evoking prospective application for brain-computer interfacing.