Chromatic characterization of novel multicolor reflective display with electrochemically size-controlled silver nanoparticles

摘要

Multifunctional electrochromic materials that enable control of multiple colors, color density, and specular reflection are potential candidates for novel reflective display devices. In this research, we focus on Ag nanoparticles that exhibit various optical states based on 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 investigate here the electrochemical formation of size-controlled Ag nanoparticles using a voltage-step method that consists of an application of two successive different voltages (V_1 and V_2). The electrochemically deposited Ag nanoparticles appear red and blue depending on the time for V_2 voltage application. The color changes between the transparent and colored states are reversible. Then, we successfully demonstrate the first LSPR-based multicolor electrochromic device in which reversible control of five optical states-transparent, silver mirror, red, blue, and black-is possible.