Design Criteria for Ultrathin Single‐Layer Flash Memristors from an Organic Polyradical

Abstract

The quest for memory devices with “flash” properties, suitable to retain information without any external power source but capable of satisfying the thinness requirements of next‐generation electronics, demands the development of device architectures with a homogeneous layer of active material that can be made as thin as possible. Here, an ultrathin memory device is presented in which the active layer is formed by a 10‐nm homogeneous film of poly‐[1,5‐diisopropyl‐3‐(cis‐5‐norbornene‐exo‐2,3‐dicarboxiimide) 6‐oxoverdazyl] (P6OV) a polyradical with three tunable charge states per radical monomer: positive, neutral, and negative. To the best of our knowledge, these are the thinnest organic flash memristors obtained to date. Careful engineering of the anode and cathode work functions, specifically aligning them with the negative and positive energy levels of the polyradical, is vital to maximize the on/off current ratio and ensure flash operation. Conversely, devices in which the cathode work function aligns with the neutral energy level of P6OV are writable only once. The bistability of this memristors is assigned to two distinct transport regimes in organic polyradicals: extended states and Poole–Frenkel.