Electrochemical and Electronic Properties of Transparent Coating from Highly Solution Processable Graphene Using Block Copolymer Supramolecular Assembly: Application toward Metal Ion Sensing and Resistive Switching Memory

Abstract

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/cm 2 at a current density of 2.66 μA/cm 2 and good electrochemical stability. The pendent P4VP chains present in the composite thin film were further exploited for electrochemical detection of metal ions. The electrical measurement of the thin film sandwich structure of the composite shows a bipolar resistive switching memory with hysteresis-like current–voltage characteristics and electrical bistability. The OFF state shows ohmic conduction at a lower voltage and trap-free space-charge-limited current (SCLC) conduction at high voltage, whereas the ON state conduction is controlled by ohmic at low bias voltage, trap-free SCLC at moderate voltage, and tarp-assisted SCLC at high voltage.

Biomemristic Behavior for Water-Soluble Chitosan Blended with Graphene Quantum Dot Nanocomposite

“…This might be caused by intermolecular motions involved in intermolecular associations via hydrogen bonding [40]. Through hydrogen bonding between CCS and GQDs, the successful nanocomposite formation could be verified [24]. To further explore the morphological and cross-sectional profiles of CCS:GQDs nanocomposite films, the surface microstructure was observed by SEM ( Figure 4a-f).…”

“…Moreover, compact structures were observed in the cross-sections of CCS:GQDs nanocomposite films, as indicated in Figure 4g-i. These bulges might be attributed to the hydrogen bonding interaction between CCS and GQDs, because CCS might act as a binder to bind GQDs, which may then form aggregates to make a difference to the morphology [24].…”

“…For the HRS, the I-V relationship became nonlinear as space-charge limited conductance (SCLC) dominated. On the log-log scale, the curve at the low voltage region of the HRS showed a linear relationship, signifying Ohmic conduction, whereas the slope of the I-V curve increased to 2 or exceeded 2 at the high voltage region, which revealed trap-free or trap-limited SCLC [24,41]. Because CCS behaved like an insulator [42][43][44][45], the fitting curves on experimental data further confirmed that the conduction mechanisms might be attributed to charge trapping-detrapping in the CCS:GQDs nanocomposite film.…”

Aligned Proton‐Conducting Graphene Sheets via Block Copolymer Supramolecular Assembly and Their Application for Highly Transparent Moisture‐Sensing Conductive Coating

“…Graphene/reduced graphene oxide (rGO) which is atomically thin two dimensional (2D) novel carbon materials with sp 2 hybridized carbon, posses extraordinary electrical, optical, mechanical and thermal properties. Hence, 2D graphene has been proposed as emerging material for varieties of potential devices such as electronics and optoelectronics, memory, sensors, energy harvesting, storage and biomedical devices . Because of the specific and interesting properties of GO, such as a two‐dimensional (2D) platform structure with numerous oxygen functional groups like ‐O‐, ‐OH, ‐COOH and epoxy groups extended outward, GO‐based materials are considered to be good candidates for fabricating proton conducting and efficient humid sensing materials .…”

“…Graphene oxide (GO) and its derivatives have been blended with different proton conducting materials or polymer electrolytes with an aim of fabricating superior proton‐conducting materials . However, achieving graphene‐polymer nanocomposites with good dispersion is an ongoing challenge owing to their strong agglomeration and settling of graphene, especially at higher loading conditions . Previous literature survey shows that covalent bonding with functional molecules was chosen as major strategy to obtain functionalized GO material for efficient proton conducting material .…”