Fabrication of PEDOT:PSS/WO3 films on indium tin oxide based glass and flexible substrates for smart windows application

Electrochromic devices (ECDs) have received extensive attentions because of their promising characteristics and applications in development of optoelectronic devices such as smart windows. The smart windows may be used to block the sunlight and maintain the comfortable temperature of the buildings. Tungsten trioxide (WO3) is one of the most efficient electrochromic material for the construction of ECDs based smart windows. In this study, we reported the fabrication of WO3 thin films based ECDs which demonstrated good electrochromic performance. Furthermore, poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) with different weight percentage (0.05 wt%, 0.1 wt% and 0.2 wt%) has been introduced to improve the conductivity and electrochromic performance of the WO3 based ECDs. The prepared thin films have been characterized by sophisticated techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The WO3 based ECDs shows coloration efficiency (C.E.) of 51 cm2/C which is improved to 62 cm2/C for PEDOT:PSS (0.1)/WO3 based ECDs. The optimum electrochromic performance was exhibited by PEDOT:PSS(0.1 %)/WO3 based ECDs, with 77 % of optical contrast (ΔT) along with stable performance over 10,000 cycles under applied voltage of 0 to −1.2 V. In addition, we also demonstrated the potential application of PEDOT:PSS(0.1 %)/WO3 as EC material for the development of flexible ECDs. The developed flexible ECDs also exhibit good electrochromic performance. This work proposed the potential of PEDOT:PSS(0.1 %)/WO3 as EC layer for the development of non-flexible and flexible ECDs.