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As the most likely prospect for the construction of neuromorphic networks, the emulation of synaptic responses with memristors has attracted attention in both the microelectronic industries and the academic environment. To that end, a newly synthesized hybrid conjugated polymer with pendant carbazole rings, that is, poly(4-(6-(9 H -carbazol-9-yl)hexyl)-4 H -dithieno[3,2- b :2′,3′- d ]pyrrole) (pC6DTP), was employed in the fabrication of a two-terminal memristor with a Al/pC6DTP/ITO configuration where the polymer was electrochemically doped. Signature biological synaptic responses to voltage spikes were demonstrated, such as potentiation & depression and spike timing dependent plasticity. The device was able to be programed through a 1 mV pulse, requiring only 100 fJ of energy. The voltage-dependent conductive nature of the polymer was speculated to occur through two synergistic mechanisms, one associated with the conjugation along the backbone of the conjugated polymer and one mechanism associated with the pendant heterocyclic rings. 

A non‐volatile conjugated polymer‐based electrochemical memristor (cPECM), derived from sodium 4‐[(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐2‐yl)methoxy]butane‐2‐sulfonate (S‐EDOT), is fabricated through roll‐to‐roll printing and exhibited neuromorphic properties. The 3‐terminal device employed a “read” channel where conductivity of the water‐soluble, self‐doped S‐PEDOT is equated to synaptic weight and was electrically decoupled from the programming electrode. For the model system, a +2500 mV programming pulse of 100 ms duration resulted in a 0.136 μS resolution in conductivity change, giving over 1000 distinct conductivity states for one cycle. The minimum programming power requirements of the cPECM was 0.31 pJ mm⁻²and with advanced printing techniques, a 0.1 fJ requirement for a 20 μm device is achievable. The mathematical operations of addition, subtraction, multiplication, and division are demonstrated with a single cPECM, as well as the logic gates AND, OR, NAND, and NOR. This demonstration of a printed cPECM is the first step toward the implementation of a mass produced electrochemical memristor that combines information storage and processing and may allow for the realization of printable artificial neural networks.

 

A memristor is a two‐terminal electronic device whose observed conductance is dependent on the history of the voltage that has been applied across the device. In this effort, poly(11‐(9H‐carbazol‐9‐yl)undecyl methacrylate) (PUMA) is fabricated into a two‐terminal device with Al and ITO electrodes and exhibits a number of signature memristor characteristics such as an irreversible transition from an insulator to a conductor at a specific DC voltage and hysteresis in the AC response. A PUMA‐based device could transition through a multitude of conductance states with varying voltage, allowing the device to exhibit spike‐timing‐dependent‐plasticity, an essential feature in replicating the behavior of biological synapses.