PEDOT: PSS/GO based three electrode photo supercapacitor to harness light energy and storage

Abstract

The potential use of photo-powered energy storage devices in smart electronics has attracted a lot of attention due to the emerging power crisis in the world. Therefore, a device capable of simultaneous energy harvesting and storage is crucial. This effort involved the fabrication of a photo-supercapacitor comprising three electrodes. A dye-sensitized photoanode and two graphite electrodes coated with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate and graphene oxide (PEDOT: PSS/GO) were utilized as the three electrodes. In the fabrication process of the device, a gel polymer electrolyte was integrated between a five-layer TiO₂- based photoanode and the middle electrode, as the dye-sensitized solar cell (DSSC). The middle and counter electrodes of the supercapacitor were separated by a filter paper soaked with KOH. The bifunctional middle electrode, which serves as both an electrode for the supercapacitor and a counter electrode for the DSSC to allow electrolyte regeneration, was a double-sided coated electrode based on PEDOT: PSS/GO. Also, a comparison was conducted between PEDOT: PSS/GO and PEDOT: PSS/GO/Ascorbic acid-based photo supercapacitors. Ascorbic acid was added as a dispersing as well as GO-reducing agent. Before the assembly of the hybrid device, the DSSC, and the supercapacitor were analyzed separately. The performance of the fabricated photo supercapacitor was then evaluated under a light intensity of 1000 W m⁻². The photo supercapacitor utilizing PEDOT: PSS/GO-based middle and counter electrode was able to achieve a power conversion efficiency of 1.14%, open circuit voltage (Voc) of 0.66 mV, current density (Jsc) of 4.35 mA cm⁻², a fill factor (FF) of 0.40 and a specific capacitance of 3.22 F g⁻¹. The PEDOT: PSS/GO nanocomposite optimized the electrical double layer capacitance provided by individual GO sheets and the photo capacitive contribution of redox- active PEDOT: PSS. The results show that the photo convertibility, FF, and Voc are higher in PEDOT: PSS/GO system compared to the ascorbic acid-based system.