Tailoring of electrical and optical properties of regenerated silk fibroin films with metal oxides
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Tailoring of electrical and optical properties of regenerated silk fibroin films with metal oxides Reetu Yadav1 and Roli Purwar1,* 1
Discipline of Polymer Science and Chemical Technology, Department of Applied Chemistry, Delhi Technological University, Shahbad Daulatpur, Bawana Road, Delhi 110042, India
Received: 2 July 2020
ABSTRACT
Accepted: 23 August 2020
In this study, silk fibroin was used as a matrix to incorporate the metal oxide nanoparticles i.e. zinc oxide (ZnO) and copper oxide (CuO) to form transparent nanocomposite films by solvent casting method. The effect of metal oxide nanoparticles and their concentrations on the conductivity of silk fibroin film were detected by a four-point probe instrument. As the thickness of the films was reduced, the conductivity increased. Hall Effect experiment was carried out to determine the carrier (electron or holes) concentration and identification of the semiconducting behaviour of nanocomposite films. Pure silk fibroin (SF) film showed p-type semiconducting behaviour. Incorporation of zinc oxide and copper oxide nanoparticles in the silk fibroin matrix makes it n-type and p-type semiconductor, respectively. Uniform dispersion of metal oxide nanoparticles in the silk fibroin matrix was observed through field emission scanning electron microscopy. The UV–Vis spectra of nanocomposite films showed 82–84% transmittance and reduction in refractive index. Addition of metal oxide nanoparticles reduced the b sheet content and percentage crystallinity of silk fibroin as observed by FTIR and XRD, respectively. The structural alterations at the molecular level reveal their relationship with electrical and optical properties.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction The aspiration to fabricate electronic devices using green materials has opened new avenues in the field of biomaterial research [1, 2]. Bombyx mori-derived silk fibroin, one of the most abundant protein, has recently been found to be a promising choice for organic electronics due to its solution processability, tailored mechanical properties, thermal stability,
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https://doi.org/10.1007/s10854-020-04332-4
optical properties, biodegradability, and biocompatibility [3, 4]. Regenerated silk fibroin films are reported to be highly insulating with electrical conductivity in the range of 10–9 to 10–15 S cm-1 [1, 5]. Recently, efforts have been given by various research groups to enhance the conductivity of the regenerated silk fibroin films to develop material for biosensors, flexible organic light-emitting diodes, and wearable electronic textiles [6–11]. The conductivity
J Mater Sci: Mater Electron
of the regenerated silk fibroin films can be enhanced either by blending with conducting polymers such as polypyrrole, polyaniline, or by the formation of nanocomposites using conductive nanostructure materials such as single-wall carbon nanotubes, multiwalled carbon nanotubes, graphene, silver and gold nanoparticles
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