Abstract
Composite films based on conducting polymers and carbon nanomaterials have attracted much attention for applications in various devices, such as chemical sensors, light-emitting diodes (LEDs), organic solar cells (OSCs), among others. Graphene oxide (GO) is an ideal filler for polymeric matrices due to its unique properties. However, GO needs to be functionalized to improve its solubility in common solvents and enable the processing by low-cost solution deposition methods. In this work, hexamethylene diisocyanate (HDI)-modified GO and its nanocomposites with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) were developed, and their morphology, thermal, electrical, thermoelectrical and mechanical performance were characterized. The influence of the HDI functionalization degree and concentration on the nanocomposite properties were assessed. The HDI-GO increased the crystallinity, lamella stacking and interchain coupling of PEDOT:PSS chains. A strong improvement in electrical conductivity, thermal stability, Young’s modulus and tensile strength was found, showing an optimum combination at 2 wt% loading. Drop and spin casting techniques were applied onto different substrates, and the results from deposition tests were analyzed by atomic force microscopy (AFM) and UV–vis spectroscopy. A number of parameters influencing the depositions process, namely solvent nature, sonication conditions and ozone plasma treatment, have been explored. This study paves the way for further research on conducting polymer/modified GO nanocomposites to optimize their composition and properties (i.e., transparency) for use in devices such as OSCs.
Highlights
Conducting polymers represent a class of organic polymers that can be semiconductors or exhibit metallic conductivity and typically possess advantageous properties for processing, which makes them very attractive for a wide range of applications in energy storage and conversion electronic [1,2,3,4,5,6]
In order to assess the morphology of the prepared hexamethylene diisocyanate (HDI)-graphene oxide (GO) samples, as thin film or interfaces, atomic force microscopy (AFM) microscopy in the non-contact mode was used
Nanocomposites made of conductive PEDOT:PSS reinforced with different amounts of HDI-functionalized GO, with two different functionalization degrees, have been manufactured, and their morphology, thermal, electrical, thermoelectrical and mechanical performance have been investigated
Summary
Conducting polymers represent a class of organic polymers that can be semiconductors or exhibit metallic conductivity and typically possess advantageous properties for processing (e.g., light-weight, solubility or good dispersibility), which makes them very attractive for a wide range of applications in energy storage and conversion electronic [1,2,3,4,5,6]. Since graphene does not comprise any reactive functional groups, its surface is inert and its interaction with the polymer matrix is weak, this hindering its final processing. To circumvent such drawbacks, graphene can be modified via oxidation to yield graphene oxide (GO), which comprises oxygenated surface groups, namely epoxy and hydroxyl on the basal planes and carboxylic acids on the edges. The exfoliation of GO in organic solvents is restricted due to strong hydrogen bonding interactions between adjacent layers
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