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

Abstract

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 10(8) 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.

High performance resistive switching memory organic films prepared through PPy growing on graphene oxide substrate

“…When the trap sites are filled, the conducting paths are erected as a result, the current increases abruptly with the device switching from the OFF state to the ON state. It is found that the ITO/GO-PPy/Al device shows considerably weak OFF-state currents (10 -8 A), more than four orders of magnitude lower than the OFF-state currents of the RRAM devices prepared from the composites of graphene and conducting polymers (10 -3 -10 -4 A) [13][14][15][16]. The low OFF-state current implies that the GO-PPy film owns a plenty of electron trap.…”

“…The OFF state of the device can be read (Sweep 4) and reprogrammed to the ON state in the subsequent positive sweep (Sweep 5), thus completing the ''write-read-erase-read-rewrite'' cycle for a nonvolatile rewritable memory device. It is seen that the two resistance states remain stable even after the voltage is removed, indicating the nonvolatile memory [16]. With the ON/OFF current ratio as high as 10 5 , the reversible resistance switching between HRS and LRS promises to be used in the rewritable data storage system.…”

“…It was reported that as trithiocarbonate was grafted onto the GO sheets, PVK was synthesized at the surface of GO via the reversible addition fragmentation chain transfer [14]. Moreover, the polyazomethine and polyfluorene derivatives have been purposely synthesized for reacting with GO covered with acyl chloride moieties [7,15,16]. The electrical switching and rewritable memory effect have been observed for those composite materials as above.…”

Macromolecular Memory

“…Graphene can give rise to bipolar switching [49] and sometimes WORM [50] memory effects. Graphene oxide functionalized with polymer chains gives a solution processable macromolecular material, displaying memory effects in combination with ITO and Al electrodes [51][52][53]. Finally, amorphous carbon and diamond-like carbon are amorphous carbon allotropes that show electronic memory effects in MIM devices.…”

Synthesis and memory performance of a conjugated polymer with an integrated fluorene, carbazole and oxadiazole backbone

“…7 In our previous work, we designed a series of D-A-type functional polymers. [8][9][10][11][12][13][14][15][16][17][18][19] The device based on conjugated poly[9,9-bis(4-diphenylaminophenyl)-2,7-fluorene] donors covalently bridged with Disperse Red 1 acceptors (DR1-PDPAF-DR1) exhibited an accessible rewritable memory characteristic. 10,17 The excitation of donor promoted CT to the conjugated channel, finally the electrons were at LUMO1 or further at LUMO2 and gave rise to a conductive charge separation state.…”