A poly(3,4-propylenedioxythiophene)/carbon micro-sphere-bismuth nanoflake composite and multifunctional Co-doped graphene for a benchmark photo-supercapacitor

Abstract

Efficient storage of sunlight in the form of charge is accomplished by designing and implementing a photo-supercapacitor (PSC) with a novel, cost-effective architecture. Sulfur (S)- and nitrogen (N)-doped graphene particles (SNGPs) are incorporated in a TiO₂/CdS photoanode. The beneficial effects of SNGPs such as the high electrical conductance promoting fast electron transfer to TiO₂, a suitably positioned conduction band that maximizes charge separation, and its' ability to absorb red photons translate into a power conversion efficiency of 9.4%, for the champion cell. A new composite of poly(3,4-propylenedioxythiophene)/carbon micro-sphere-bismuth nanoflakes (PProDOT/CMS-BiNF) is integrated with the photoanode to yield the PSC. The photocurrent produced under 1 sun irradiance is directed to the supercapacitor, wherein, the synergy between the faradaic and electrical double layer charge accumulation mechanisms of PProDOT and CMS-BiNF bestows storage parameters of an areal capacitance of 104.6 mF cm⁻², and energy and power densities of 9 μW h cm⁻² and 0.026 mW cm⁻². An overall photo-conversion and storage efficiency of 6.8% and an energy storage efficiency of 72% exhibited by the PSC are much superior to those delivered by a majority of the PSCs reported in the literature on the otherwise highly efficient perovskite solar cell or the expensive Ru dye based solar cells.