Electro-grafted organic memristors: Properties and prospects for artificial neural networks based on STDP

The capabilities of memristors to serve as artificial synapses in neural network type of circuits have been recently recognized. These two-terminal analog memory devices offer valuable advantages in terms of circuit architectures. In particular, with their room temperature processes and large diversity coming from chemistry, organic memristors represent a chance to develop devices that can be densely integrated above-IC. In this article, we present a new class of organic resistive memory based on a robust electrografted redox thin film as active material integrated in a planar metal/organic/metal topology. The combination of a specific redox polymer and of the electro-grafting technique leading to fully covalent films makes such organic memristors particularly robust. The devices display high RMAX/RMIN ratio, long retention time and multi-level conductivity. The potential of these devices to store analog synaptic weights in neural network circuit strategies is shown by demonstrating their compatibility with the Spike Timing Dependence Plasticity (STDP) learning rule and by implementing the associative memory function.