PEDOT:PSS-V2O5 Hybrid for Color Adjustement in Electrochromic Systems
Romain Futsch, Issam Mjejri, Harena Rakotozafy, Aline Rougier
Abstract
Electrochromism is known as a modulation of the optical properties under an applied voltage. Used in various applications, aside to the commercialized smart windows based on transmissive electrochromic devices (ECDs), the opaque systems have received significant interest for displays purposes. Herein, in a novel approach to adjust color, electrochromic oxides with high EC performance were chosen as additives to commercialized conductive polymer inks. More precisely opaque films were deposited (using Bar Coater) from mixtures of V2O5, synthesized by polyol process, with poly(3,4-ethylenedioxythiophene, polystyrene sulfonate) PEDOT:PSS commercial ink in different weight percentages (wt%) ranging from 0 to 100 (V2O5 wt%) with thickness of few hundred nms to few ms. As-deposited films colors range from blue for PEDOT:PSS to orange for V2O5. PEDOT:PSS-V2O5 films exhibit significant electrochromic properties associated with a good electrochemical stability. In the series, the hybrid film with 90 wt%-10 wt% PEDOT:PSS-V2O5 shows a reversible behaviour with significant reflectance modulation (ΔR≈20.5% at 550 nm) in lithium based electrolyte and a good contrast (∆E* > 30). The maximum contrast was reached for 3.7 µm thick layer. Our results indicate that the hybrid film, combining the benefit of mixing inorganic and organic materials, are promising materials for enhancing electrochromic devices color and inorganic electrochromic powder processability on large scale.