Dual-function electrochromic supercapacitor with graphene electrode

Abstract

In order to the immense demand for the development of energy-storage systems, layer-optimized graphene and chemically modified poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) were utilized as the electrode and electrochemical material, respectively, to fabricate a device that exhibited electrochromic and supercapacitive functions. The electrochemical properties of the device with the graphene electrode were compared with those of a similar device with ITO as the electrode, and a remarkable synergetic effect was observed in the former, likely owing to strong π-π interactions between graphene and PEDOT:PSS. The colored and bleached transmittances of the device with the graphene electrode were 20.6% and 59.3%, respectively, at a wavelength of 650 nm, which are indicative of its electrochromic behavior. Furthermore, the galvanostatic charge/discharge curves, which are indicative of the electrochemical-energy-storage performances, were in good agreement with the clearly visible transmittance change of the device. The device with the graphene electrode exhibited a maximum areal capacitance of 1.08 mF cm−2 at a current density of 0.001 mA cm−2, which was higher than that of the ITO-based electrode. Our approach for fabricating graphene devices with modified PEDOT:PSS could be helpful in designing dual-function devices for promising electrochromic energy-storage platforms.