High On/Off Ratio Organic Resistive Switching Memory Based on Carbazolyl Dicyanobenzene and a Polymer Composite

We reported a high on/off ratio organic resistive switching memory (ORSM) based on carbazolyl dicyanobenzene and the poly(3-hexylthiophene) (P3HT) composite. Two carbazolyl dicyanobenzene molecules, which were 2,4,5,6-tetrakis(carbazol-9-yl)-1,3-dicyanobenzene (4CzIPN) and 4,5-bis(carbazol-9-yl)-1,2-dicyanobenzene (2CzPN), were selected due to their low mobility and enormous steric hindrance. The ORSM exhibited non-volatile and bipolar memory properties with the on/off ratio of exceeding 105, retention time of more than 5 × 104 s, enduring ability of 150 times, "SET" voltage (Vset) of −6 V, and "RESET" voltage (Vreset) of 3.3 V. The large steric hindrance of 4CzIPN and 2CzPN led to a strong barrier between P3HT and 4CzIPN or 2CzPN, by which the intermolecular interaction was prohibited and the current leakage was sufficiently suppressed, leading to the enhanced on/off ratio. The mechanism of the switching was the filling and vacant process of the charge traps induced by 4CzIPN and 2CzPN, as well as the inherent traps in P3HT bulk. The negative or positive bias triggered the trapping and detrapping process, which led to the transforming of the conductive way of charges, resulting in the resistive switching effect. The study enlightens a new strategy to enhance the performance of the ORSM and facilitates their electronic application in the future.