Deciphering dielectric and morphological contributions to EMI shielding in conducting polymers: a comparative study of PANI and PEDOT:PSS

Conducting polymers (CPs) are evolving as capable candidates for electromagnetic interference (EMI) shielding applications owing to their tunable conductivity, structural versatility, and lightweight nature. In this study, we systematically compare the optical, structural, morphological, and dielectric properties of two prominent CPs viz. polyaniline (PANI) and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) for EMI shielding applications in the technologically relevant K-band region (18-26.5 GHz). Characterizations were performed using UV-Visible (UV-Vis) absorption spectroscopy, Fourier-Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), dielectric analysis, and Vector Network Analyzer (VNA) measurements. The results indicate that PANI shows the highest EMI shielding effectiveness (SE), followed by PEDOT:PSS, owing to their considerable electrical conductivity and optimized charge transport properties. PANI exhibits a specific shielding effectiveness (SSE) of 42.99 dB.cm³.g⁻¹, which is approximately 1.3 times higher than that of PEDOT:PSS (33.97 dB.cm³.g⁻¹). Dielectric measurements of PANI and PEDOT:PSS reveal a strong correlation between polarization mechanisms and shielding behaviour, further reinforcing the advantage of CP-based systems in EMI shielding applications. This comparative study provides valuable insights into the structure-property relationships of CPs and highlights their potential for advanced EMI shielding and dielectric applications in next-generation 5G communication systems, wearable electronics, and other emerging electronic and telecommunication technologies.