One-step inkjet printing of tungsten oxide-poly(3,4-ethylenedioxythiophene):polystyrene sulphonate hybrid film and its applications in electrochromic devices

Hybrid film comprised tungsten oxide and poly (3,4-ethylenedioxythiophene):polystyrene sulphonate (WO3-PEDOT:PSS) was developed by applying one-step inkjet printing from an office inkjet printer. The WO3 nanoparticles were synthesized from commercial crystalline WO3 powder through a wet ball-milling process, which is a simple, environmentally friendly, and cost-effective method of using water as a green solvent and low-energy milling. The WO3-PEDOT:PSS inkjet ink was prepared by dispersing the as-milled WO3 and PEDOT:PSS in n-propanol and deionized water. The inkjet-printed WO3-PEDOT:PSS thin films show marked improvements of cathodic electrochromism over WO3 films: the transmittance change of 20% at 550 nm (visible region) and 35% at 900 nm (infrared region) along with the response time of 5.67/0.30 s in their colored/bleached state, and the electrochromic coloration efficiency of 27.86 cm2/C at 550 nm and 69.64 cm2/C at 900 nm.