Viologen-bridged polyaniline based multifunctional heterofilms for all-solid-state supercapacitors and memory devices

Both the viologen and polyaniline (PANI) have shown high electrochemical redox activity that can be used to fabricate optoelectronic, electronic and energy storage devices as well as sensors. However, it still remains great challenge for integrating these two fascinating materials together via covalent linkage to avoid phase separation in physical mixtures. In this work, a novel viologen-bridged polyaniline film (hereafter called as VBP) onto the indium-tin-oxide (ITO) glass was prepared by one-step electropolymerization approach, and then the in-situ synthesized golden nanoparticles (AuNPs) were sandwiched between the VBP films to produce the heterofilms (VBP|Au|VBP) as active materials. The VBP|Au|VBP-based electronic memory device and all-solid-state supercapacitor, which exhibited bistable nonvolatile rewritable memory performance with high ON/OFF current ratio of 10⁵ and high volumetric capacitance up to 6.22 Fcm⁻³, respectively, were fabricated through simple layer-by-layer method. This work not only offers a new and easy strategy for synthesizing viologen-bridged PANI materials through covalent bonding, but also paves the way for the development of high-efficient sandwich-type resistive random access memory (RRAM) devices and the all-solid-state supercapacitors based on rational designed heterofilms.