Voltage-heating responsive and patternable solvatochromism display utilizing nickel complex-Nafion film composites

In this work, a voltage-heating actuated flexible solvatochromic film is developed using the composites of Nafion film-nickel complexes with spray-coated silver nanowires (AgNWs). The nickel complexes, inside Nafion film through ion exchange, serve as colorable components due to the coordination number change of water molecules in solvatochromism. The color-changing process of the composites was characterized experimentally by adjusting the water content in films, which exhibit distinct coloration properties from red to green with an absorbency shift (0.25–0.60 at 420–550 nm). To achieve an electrical actuation, the electrothermal joule effect of AgNWs is studied to accelerate the hydrolysis of the nickel complexes. A mask patterned spraying process is developed to increase the adhesion between AgNWs and Nafion film, which can be beneficial in a low (2–5 V) voltage-regulated coloration. This study provides a systematic investigation of flexible electrothermally responsive color-changing film of complex metal ions, the composite film prepared from flexible smart materials and well-adhered electrodes have potential applications in the fields of adaptive camouflage, wearable display devices and e-skins.