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 (V
set) of
−6 V, and “RESET” voltage (V
reset) 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.