Nonvolatile Rewritable Memory Effects in Graphene Oxide Functionalized by Conjugated Polymer Containing Fluorene and Carbazole Units

A new polymer, poly[{9,9‐di(triphenylamine)fluorene}(9,9‐dihexylfluorene)(4‐aminophenylcarbazole)] (PFCz) was synthesized and used in a reaction with graphene oxide (GO) containing surface‐bonded acyl chloride moieties to give a soluble GO‐based polymer material GO–PFCz. A bistable electrical switching effect was observed in an electronic device in which the GO–PFCz film was sandwiched between indium–tin oxide (ITO) and Al electrodes. This device exhibited two accessible conductivity states, that is, a low‐conductivity (OFF) state and a high‐conductivity (ON) state, and can be switched to the ON state under a negative electrical sweep; it can also be reset to the initial OFF state by a reverse (positive) electrical sweep. The ON state is nonvolatile and can withstand a constant voltage stress of −1 V for 3 h and 108 read cycles at −1 V under ambient conditions. The nonvolatile nature of the ON state and the ability to write, read, and erase the electrical states, fulfill the functionality of a rewritable memory. The mechanism associated with the memory effects was elucidated from molecular simulation results and in‐situ photoluminescence spectra of the GO–PFCz film under different electrical biases. Polymer memory: A newly synthesized soluble graphene oxide (GO) covalently functionalized with poly[{9,9‐di(triphenylamine)fluorene}(9,9‐dihexylfluorene)(4‐aminophenylcarbazole)] (PFCz) exhibits a typical bistable electrical switching and nonvolatile rewritable memory effect, with a turn‐on voltage of about −1.3 V and an ON/OFF state current ratio of more than 103.