Electrochromism refers to the reversible color change phenomenon under an applied voltage, which demonstrates wide application potential in information displays and optical modulation devices. Conductive polymers, an important type of electrochromic materials, have gained wide attention for their simple preparation process, cost-effectiveness, fast response speed, and good cycling stability. Electrochromic devices utilizing local surface plasmon resonance based on metallic deposition have also attracted great interest. By controlling the reduction of metal cations, the deposition of metal particles or films can be achieved, which allows control over the device's color or reflection state. Herein, electrochromic nanocomposites combining silver nanowires and polyaniline were synthesized using a self-assembly method to create composite thin film electrodes exhibiting both the electrochromic and local surface plasmon resonance effects. The obtained electrode can satisfy the inherent electrochromic effect of polyaniline itself, which means the reversible variation from light green to deep purple. Meanwhile, under further negative potential, the lower transmittance of nearly 0 % of the black state can be achieved. This is because silver nanowires are oxidized into silver ions at a positive potential, and then reduced to elemental silver under the action of a negative potential, absorbing a large amount of light. In addition, different from traditional electrochromic devices based on the single silver ion, the as-prepared electrodes demonstrate reversible modulation due to the adsorption of silver ions by amine groups on aniline, which can effectively reduce the diffusion of silver ions into the electrolyte and thus improving the stability of this combined electrochromic effect. The electrode displays a dark-colored state with 25.4% transmittance at a positive potential. Upon application of a reverse potential, the electrode transitions to a faded state (83.3%), followed by a return to a dark-colored state (10.7%) at a higher reverse potential. This dual-colored state, not achievable by conventional electrochromic devices, opens up new possibilities in the fields of information display and optical modulation.

Key words: Electrochromic, Conductive polymer, Local surface plasmon resonance, Silver nanowires