Bismuth Nanogratings With Narrow Plasmon Resonances for Dynamic Polarized Color Generation and Colorimetric Sensing

ABSTRACT Bismuth nanostructures are appealing for sustainable color generation and sunlight harvesting, thanks to their non‐toxicity and their tunable visible‐to‐near‐infrared interband plasmon resonances. However, owing to their broad and polarization‐insensitive spectral features, the nanostructures reported so far displayed a limited color tunability and lacked other functionalities such as sensing. Herein, we report bismuth nanogratings with polarization‐sensitive and narrow diffraction‐induced and Fano plasmonic resonances (quality factor Q > 10 and up to 100). They were fabricated on the cm 2 scale by conformal pulsed laser deposition of bismuth onto the nanostructured layers of DVDs. Specular reflectance measurements reveal plasmonic resonances only when light is polarized in the plane perpendicular to the lines, and these resonances shift across the visible‐to‐near infrared upon changing the angle of incidence. This results in well‐contrasted, polarization‐sensitive colors, which are iridescent only for a perpendicularly oriented polarization. Resonances strongly shift upon changing the refractive index of the surrounding medium (> 500 nm/RIU), resulting in a marked change in the plasmonic color, e.g., from green in air to red in water. This showcases the potential of these nanogratings for dynamic polarized color generation, colorimetric sensing, photocatalysis and optoelectronics, harnessing the non‐conventional interband plasmonic character of bismuth.