Electrochemical and Electronic Properties of TransparentCoating from Highly Solution Processable Graphene Using Block CopolymerSupramolecular Assembly: Application toward Metal Ion Sensing andResistive Switching Memory

摘要

Here, we have discussed the preparation of a highly solution processable graphene from a novel supramolecular assembly consisting of block copolymer polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) and pyrenebutyric acid (PBA)-modified reduced graphene oxide (RGO). The PBA molecules anchored on the graphene surface form supramolecules with PS-b-P4VP through H-bonding between the carboxylic acid group of 1-pyrenebutyric acid and the pyridine ring of P4VP. The formation of a supramolecular assembly results in a highly stable solution of reduced graphene oxide in common organic solvents, such as 1,4-dioxane and chloroform. Highly transparent and mechanically stable thin films can be deposited from these supramolecular assemblies on a relatively smooth surface of different substrates such as silicon wafer, glass, indium tin oxide, and flexible polymer substrates like poly(ethylene terephthalate). The graphene surface modifier (PBA) can be selectively removed from the thin film of the hybrid material by simple dissolution, resulting in a porous structure. Hybrid thin films of around 50 nm thickness exhibit interesting electrochemical properties with an areal capacitance value of 17.73 μF/cm² at a current density of 2.66 μA/cm² andgood electrochemical stability. The pendent P4VP chains present inthe composite thin film were further exploited for electrochemicaldetection of metal ions. The electrical measurement of the thin filmsandwich structure of the composite shows a bipolar resistive switchingmemory with hysteresis-like current–voltage characteristicsand electrical bistability. The OFF state shows ohmic conduction ata lower voltage and trap-free space-charge-limited current (SCLC)conduction at high voltage, whereas the ON state conduction is controlledby ohmic at low bias voltage, trap-free SCLC at moderate voltage, andtarp-assisted SCLC at high voltage.