Influence of molecular weight of PVP on the structure of silver nanowires for EMI shielding application

A material with high visual transparency and excellent electromagnetic interference efficiency (EMI SE) at microwave frequencies is the need of the hour for emerging electronic devices. Silver nanowires (AgNWs) are the best alternative to match the commercially used indium tin oxide (ITO) films. Poly (vinylpyrrolidone) (PVP), being the crucial parameter in the preparation of AgNWs, plays an important role in deciding the crystallinity and aspect ratio of AgNWs. In this paper, the molecular weight of PVP is varied (40000, 360000, and 1300000) by keeping other parameters constant in the modified polyol method to understand the structural and morphological properties of the prepared AgNWs. As-synthesized AgNWs are spin-coated on the glass substrate and studied for visible transparency and EMI shielding performance. It is found that optical transparency and EMI SE are inversely related. For 80% visible transparency, a shielding of 20 dB is achieved, while for 42% transparency, a shielding of 37.5 dB is achieved in the frequency range between 8 and 12 GHz.