Solution-Processed Interfacial PEDOT:PSS Assembly into Porous Tungsten Molybdenum Oxide Nanocomposite Films for Electrochromic Applications

Electrochromic devices (ECDs) have received increased attention for applications including optoelectronics, smart windows, and low-emission displays. However, it has been recognized that the ECDs with transition-metal oxide (TMO) electrodes possess a high charge transport barrier because of their poor electrical conductivity, which limits their electrochromic performance. In this work, we addressed this limitation by utilizing a conjugated polymer to fabricate an organic-inorganic nanocomposite film that decreases the charge transport barrier of typical TMO electrodes. Using a conventional spray-layer-by-layer (spray-LbL) deposition technique, we demonstrate an electrochromic film composed of porous layers of tungsten molybdenum oxide (W0.71Mo0.29O3) nanorods permeated with an interconnected conductive layer of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The introduction of PEDOT:PSS is shown to significantly reduce the charge transport barrier, allowing the nanocomposite W0.71Mo0.29O3/PEDOT:PSS electrode to exhibit significantly improved electrochromic switching kinetics compared with the deposited W0.71Mo0.29O3 films. Furthermore, the optical contrast of the nanocomposite electrode was observed to be superior to both pure PEDOT:PSS and W0.71Mo0.29O3 electrodes, with a performance that exceeded the linearly predicted contrast of combining the pure films by 23%. The enhanced performance of the PEDOT:PSS-intercalated porous W0.71Mo0.29O3 nanocomposite electrodes and the facile synthesis through a spray-LbL method demonstrate a viable strategy for preparing fast assembling high-performance nanocomposite electrodes for a wide variety of electrochemical devices.