Printed Silver Nanowire-PEDOT:PSS Composite Electrodes for Flexible Transparent Microsupercapacitor Applications

The integration of microsupercapacitors (mSCs) with flexible/wearable electronic devices can greatly advance the capabilities of these devices. In this work, a robust flexible transparent mSC is constructed using silver nanowires (Ag NWs) combined with a conducting polymer, poly­(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), which exhibits excellent electrochemical stability and cyclability. Typically, the fabrication of such composite electrodes for supercapacitors (SCs) is a multistep process requiring electro/in situ polymerization, whereas in this work, a simple two-step direct ink writing is adopted. An ink made of Ag NWs and PEDOT:PSS is used to print the electrodes in an interdigitated design. These are then coated by a [poly­(vinyl alcohol)]/H3PO4 (orthophosphoric acid) polymer electrolyte to obtain the mSC with a transparency of 84.6% at 550 nm. The optical, electrical, and electrochemical properties of the mSC are optimized by varying the concentration of Ag NWs in PEDOT:PSS. The charge-transfer resistance decreases, and the electrochemically active surface area increases with the concentration of Ag NWs. Compared with pure PEDOT:PSS electrodes, the composite electrodes exhibit significantly lower internal resistance and nearly 2.5 times higher areal capacitance. The mSC also retains its capacitance with increasing current densities, operating in a fixed voltage window of 1.2 V. The device shows excellent electrochemical stability over 10000 charge–discharge cycles along with excellent mechanical flexibility. These results show that a Ag NWs:(PEDOT:PSS)-based mSC can act as a good flexible and transparent energy source for wearable electronic applications.