Large‐Area Printed PEDOT:PSS Shielding and Frequency Selective Surface (FSS) on Textiles

Conductive polymers, such as Poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS), have been widely investigated for radio frequency (RF) and microwave electromagnetic shielding. However, achieving high frequency‐selectivity remains challenging due to their low conductivity, leading to a high sheet resistance. Herein, we report for the first time a screen‐printed, flexible frequency‐selective surface (FSS) based on multilayer PEDOT: PSS films on both rough nonwoven textiles and textured paper‐based surfaces. Bulk PEDOT: PSS films demonstrate increasing shielding effectiveness with layer thickness and conductivity that is dependent on the substrate's texture and absorbance. On nonwoven polyester/cellulose composite fabric, 20‐layer films yield a DC sheet resistance of 5 Ω/□ and a shielding effectiveness of 32 dB (98.88%) across the 3.5 to 6 GHz frequency band. A similar screen‐printed PEDOT: PSS FSS filters signals as a band‐stop filter at 4.4 GHz with a half‐power bandwidth of 450 MHz, achieving a Quality Factor of 9.2, and in‐band shielding of 13 dB, surpassing printed surfaces using metallic inks and demonstrating the suitability of conducting polymers in passive, flexible, and large‐area band‐filtering devices.