Multifunctional highly conductive cellulose nanopaper with ordered PEDOT:PSS alignment enabled by external surface area-promoted phase separation

Integrating cellulose, the most abundant biopolymer on Earth, with PEDOT:PSS, the most commercially available conducting polymer, can create multifunctional conductive nanopapers for sustainable electronics. However, conventional PEDOT:PSS/cellulose composites often exhibit limited conductivity, primarily due to the random distribution of PEDOT and the aggregation of PSS within the cellulose matrix. Herein, we introduce a confined phase separation approach that leverages the inherent physical characteristics of the cellulose substrate to enhance the performance of these composites. By systematically investigating the influence of the external surface area of nanocellulose on PEDOT:PSS coverage and composition evolution, we demonstrate that a higher external surface area ensures uniform PEDOT:PSS coating on nanocellulose networks and facilitates effective PSS removal during secondary doping. This process enhances phase separation and promotes ordered alignment of PEDOT chains along nanocellulose, resulting in an electrical conductivity of up to 252 S cm⁻¹. Such highly conductive nanopapers exhibit exceptional performances in supercapacitors and electromagnetic shielding, achieving an ultrahigh specific electromagnetic shielding effectiveness of 33,122 dB cm² g⁻¹ at only 6 μm thickness. Our study highlights the critical role of cellulose substrate selection at the nanoscale and elucidates the interactions within conducting polymers, offering a promising pathway for developing high-performance, sustainable electronics.