Carrier density tunability and encryption in plasmonic structural colors via dual-layer borophene nanodisk metasurfaces

Abstract

Structural colors are different from pigment colors. They are dominated by optical waves and micro- and nanostructures. In this work, we present a metasurface structure color device based on dual-layer borophene nanodisks (BN). By just tuning the bias voltage without changing the geometric parameters, the spectral profile can be customized. Thus, the metasurface can present specific colors. Through numerical analysis using Finite Difference Time Domain (FDTD) theory, we investigate the printed color property of the system, which achieves an ultra-high resolution of up to 10⁶ dots per inch ($dpi$) and covers 121 $\%$ of the $sRGB$ color gamut area within fixed structural parameters. In addition, as the direction of polarization switches, the system can display two color states: encrypted and non-encrypted. The metasurface also demonstrates robust performance across various incident angles. Moreover, it is capable of distinguishing between normal and basal cancer cell solutions by analyzing their color differences. These findings highlight potential applications in information encryption, polarization imaging, color sensing, and cancer detection. Besides, the research gap in the field of structural colors featuring encryption capabilities, high resolution, tunable carrier density, geometric stability, and broad color gamut coverage has been filled.