Chromatic control of multicolor electrochromic device with localized surface plasmon resonance of silver nanoparticles by voltage-step method

• Color control of electrochromic (EC) device with electrodeposited Ag nanoparticles.
• Electrochemically formed size-, number-, or connection-controlled Ag nanoparticles.
• Multiple coloration of the EC device based on localized surface plasmon resonance.
• Effect of waveforms of application voltages on Ag morphology and resultant colors.

Inorganic electrochromic (EC) materials are of interest because of their many possible applications, including use in information displays. The multifunctional EC materials that enable control of multiple colors and color depth have considerable promise as candidates for full color EC display devices. In this research, we focused on Ag nanoparticles that exhibit various colors on the basis of their localized surface plasmon resonance (LSPR). Because the LSPR band depends on the size and shape of the nanoparticles, control of the morphology of Ag nanoparticles can lead to dramatic changes in color. In order to apply this color variation for display devices, we utilized here the electrochemical formation of size-controlled Ag nanoparticles using a voltage-step method that consists of an application of two successive different voltages. In order to improve the variation of colors of the EC cell, the effect of application voltages and their times on morphology of deposited silver were investigated. The relationship between the morphology of the deposited Ag nanoparticles and color of the EC cell was discussed, and then we successfully represented multiple coloration of the EC cell with various color depth.