Metal oxide-mixed polymer-based hybrid electrochromic supercapacitor: improved efficiency and dual band switching

Abstract

Inclusion of charge storage properties to electrochromic devices has gained much interest and has evolved into a promising emerging energy related field due to multifunctional smart device application. Here, an organic-inorganic solid state asymmetric electrochromic supercapacitor device (ESCD) containing nano-CoTiO3 mixed poly-3-hexylthiophene (P3HT) and WO3 as two electrodes has been designed to study electrochromic and supercapacitor properties. The electrochemical properties of CoTiO3 show a pseudocapacitive type charge storage capability, which has been utilized to enhance the electrochromic performance of ESCD with additional charge storage ability. The device shows charge storage property with fast charging and slow discharging giving very high coulombic efficiency with the specific capacitance of 6.4 mF/cm2 at 0.2 mA/cm2 current density. The device shows excellent electrochromic supercapacitive property with color contrast of ~ 50% and small switching time of ~1 s at 515 nm wavelength with excellent cyclic stability. The device exhibits the capability to cut near infrared (NIR) wavelength (700 nm and 850 nm), and has a potential application as heat filtering device. Thus, the addition of pseudocapacitive type material in electrochromic device enhances the capacitive performance along with electrochromic properties which makes electrochromic device more suitable for real life application.