Analysis for coloration mechanism of reversible silver deposition-based electrochromic device by in situ observation of plasmonic nanoparticles with dark-field microscopy

We studied a silver (Ag) deposition-based multicolor electrochromic (EC) device that can represent mirror, black, cyan, magenta, yellow, green, and transparent states reversibly. The coloration in this system is based on localized surface plasmon resonance (LSPR) of Ag electrodeposits. The size and shape of deposited Ag nanoparticles (AgNPs) are important for device coloration. Therefore, it is necessary to elucidate the LSPR band change corresponding to the morphology of AgNPs during the EC device operation to improve the colorability. In this study, dark-field microscopy (DFM) was applied to in situ observation of the changes in LSPR of AgNPs at the coloration process in the reversible Ag deposition multicolor EC device for the first time. The light scattering observation of AgNPs using DFM enabled analysis of the LSPR band over time. The obtained light scattering spectra provide detailed information on the LSPR induced by AgNPs in Ag deposition-based EC devices in comparison with conventional absorption spectrum measurements.

Automated summary

We studied a multicolor electrochromic (EC) device that uses silver (Ag) deposition and is able to reversibly represent multiple colors. The coloration of the device is based on localized surface plasmon resonance (LSPR) of Ag nanoparticles (AgNPs). In this study, dark-field microscopy (DFM) was used for the first time to observe the changes in LSPR of AgNPs during the coloration process of the EC device. The obtained light scattering spectra provide detailed information on the LSPR induced by AgNPs in comparison with conventional absorption spectrum measurements.