Organic Memristive Devices Based on Squaraine Nanowires

Organic semiconductor devices are gaining prevalence in various technology fields due to the ease of production, tailorability, and cost. Here, we demonstrate an organic nanowire based memristor device with nonvolatile memory retention and the ability to write a variety of conductance states. Squaraine nanowires are drop-cast onto an interdigitated Au electrode array where they self-assemble into wires that span the 10 μm electrode distance. When tested with a suite of voltage pulses, the devices reveal neuromorphic memristive characteristics. We show impedance testing that reports the neuromorphic behavior independently of typical memristive I–V tests. We suggest impedance testing may be used in lieu of I–V traces at low frequencies (1–104 Hz). The dominant characteristics of the device at low frequency are resistive, but the device transitions to a capacitance dominated device at ∼400 Hz. The device retains a resistive component at higher frequencies under biases of ±2, 4 V. Multilevel memory, volatility, and rewritability are also demonstrated. Organic based neuromorphic devices will be a disruptive technology due to the ease with which the core molecule can be altered in comparison to the solid-state device equivalent as well as lower production costs.