Outstanding Absolute Electromagnetic Interference Shielding Effectiveness of Cross‐Linked PEDOT:PSS Film

Abstract Conducting polymer ultrathin films with high absolute electromagnetic interference (EMI) shielding effectiveness (SE) is highly desirable for their facile processability. The conducting polymer, poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), possesses excellent conductivity. However, a thin film of PEDOT:PSS is water soluble, making it disadvantageous for EMI shielding. Here, a cross‐linked, water‐insoluble, ultrathin film of PEDOT:PSS for EMI shielding is evaluated. A 9 ± 1 µm thick cross‐linked PEDOT:PSS film exhibits an average EMI SE of 40 dB. Standard electrodynamics simulation also confirms the experimental data. The most realistic parameter of EMI shielding for practical application is the absolute SE. The absolute SE of cross‐linked PEDOT:PSS film is obtained to be 51 480 dB cm 2 g −1 , highest ever reported. Mechanistically, the absorption predominant SE originates from the cross‐linking of PEDOT:PSS, resulting in a higher conductivity (769 S cm −1 ) and creating internal reflecting surfaces. The mechanical strength, solution processability, and outstanding absolute EMI SE make cross‐linked PEDOT:PSS film to be an attractive EMI shield for real‐time applications such as in defense arena.