Preparation and flash memory performance based on fluorene–triphenylamine copolymer (PF–TPA)/MWCNTs

A conjugated alternating polymer based on fluorene and triphenylamine, namely poly[(9,9-dioctyl)-2,7-fluorene-co-triphenylamine] (PF-TPA), in which triphenylamine (TPA) as electron donor and hole transporting group was devised and synthesized on the basis of the Suzuki coupling method. The structural properties of the copolymer can be verified by Fourier transform infrared (FT-IR) spectroscopy, hydrogen and carbon nuclear magnetic resonance (H-1-NMR, C-13-NMR). Nonvolatile memory devices with bistable electrical switching behavior were observed based on active layers of both fluorene-triphenylamine copolymer (PF-TPA) and PF-TPA: carbon nanotubes (CNTs) hybrid composite materials. Typical formed composite-based device with sandwich configuration, indium tin oxide (ITO)/PF-TPA: CNTs/Al, was demonstrated superior rewritable flash memory property compare to the ITO/PF-TPA/Al device with a greater ON/OFF state current ratio. In addition, the optimal storage characteristics occurs when the doping concentration of CNTs was at a certain value (CNTs = 0.3 mg mL(-1)), which leading to the ON/OFF state current ratio added up to 2 orders of magnitude and the switching threshold voltage reduced prominently. The conductance switching mechanism of devices was also further discussed. After testing, the devices have good stability and durability, which have a potential application value in data storage.