Polyaniline/graphene hybrid film as an effective broadband electromagnetic shield

Conducting polyaniline (PANi)-graphene (G) free standing, hybrid films were obtained by a solution intercalation method suitable for electromagnetic interference (EMI) shielding applications. The films were characterized structurally using Fourier transform infrared spectroscopy, micro-Raman spectroscopy, X-ray diffraction and scanning electron microscopy. The electrical characterization was done using Hall measurement setup to estimate the dc electrical conductivity and establish the charge carrier type and mobility and investigate the possibility of using the hybrid films in other applications. The thermal stability of the films was investigated using thermo gravimetric analysis. The EMI shielding effectiveness (SE) of the composite films was tested over a broad microwave frequency range covering 4-12 GHz (C and X bands) by waveguide transmission line technique. The films exhibit very high values of reflected power (P-r) in the range of 85-90% in the C-band and 75-80% in the X-band, respectively. A maximum total shielding effectiveness value of SET similar to 42 dB could be observed in the frequency range of 4-8 GHz and SET similar to 32 dB could be observed in the frequency range of 8-12 GHz, corresponding to more than 99.99% microwave attenuation in both the C and X bands. In the entire frequency range of analysis, contributions from reflection to the total EMI SE is very high compared to that of absorption. The results suggest that the hybrid film may be used as effective, lightweight and flexible, reflection dominated EMI shielding material in a broad range of electromagnetic spectrum.