Solution-Processed Highly Superparamagnetic and Conductive PEDOT:PSS/Fe₃O₄ Nanocomposite Films with High Transparency and High Mechanical Flexibility

Multifunctional films can have important applications. Transparent and flexible films with high conductivity and magnetic properties can be used in many areas, such as electromagnetic interference (EMI) shielding, magnetic switching, microwave absorption, and also biotechnology. Herein, novel highly conductive and superparamagnetic thin films with excellent transparency and flexibility have been demonstrated. The films were formed from a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS; Clevios PH1000) aqueous solution added with iron oxide (Fe 3 O 4 ) nanoparticles that have a size of ∼20 nm by spin-coating. The PEDOT:PSS/Fe 3 O 4 films have a high conductivity of 1080 S/cm through treatment with methylammonium iodide in an organic solvent. The high-conductivity PEDOT:PSS/Fe 3 O 4 films can also have a saturation magnetization of 25.5 emu/g and an EMI shielding effectiveness of more than 40 dB in the 8–12.5 GHz (X band) frequency range. The PEDOT:PSS/Fe 3 O 4 films have additional advantages, like excellent transparency, good mechanical flexibility, low cost, and light weight. In addition, we fabricate flexible PEDOT:PSS/Fe 3 O 4 silk threads with a high magnetism and conductivity.