Electrochromic PEDOT:PSS with Embedded Liquid Gallium Nanoparticles

Electrochromic materials enable reversible color changes under an applied electric field, making them valuable for smart windows and optoelectronic devices. Among these materials, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been extensively studied due to its broad electrochromic modulation range and solution processability. However, its electrochromic efficiency is limited by the insulating PSS component, which restricts charge transport. In this study, we explore the incorporation of electrically conductive liquid-state gallium nanoparticles (Ga NPs) into PEDOT:PSS to enhance its electrochromic performance. Electrochemical analyses revealed that the resulting composite exhibited enhanced switching kinetics and comparable optical transparency to pristine PEDOT:PSS films. The performance enhancement is attributed to the liquid state of Ga NPs, which facilitates the rapid oxidation and reduction of the interfacial Ga oxide layer. The cracked structure of the oxide layer enabled fast carrier exchange, while allowing efficient charge storage within the oxide. Notably, PEDOT:PSS with Ga NPs demonstrated the shortest response and recovery times recorded for PEDOT:PSS-based materials to date. These findings highlight the potential of Ga NP incorporation to significantly improve the electrochromic performance of PEDOT:PSS, offering promise for energy-efficient smart coatings and optoelectronic applications.