Broadband and Spectrally Selective Photothermal Conversion through Nanocluster Assembly of Disordered Plasmonic Metasurfaces

Abstract

<p>Plasmonicmetasurfaces have been realized for efficient light absorption,thereby leading to photothermal conversion through nonradiative decayof plasmonic modes. However, current plasmonic metasurfaces sufferfrom inaccessible spectral ranges, costly and time-consuming nanolithographictop-down techniques for fabrication, and difficulty of scale-up. Here,we demonstrate a new type of disordered metasurface created by denselypacking plasmonic nanoclusters of ultrasmall size on a planar opticalcavity. The system either operates as a broadband absorber or offersa reconfigurable absorption band right across the visible region,resulting in continuous wavelength-tunable photothermal conversion.We further present a method to measure the temperature of plasmonicmetasurfaces via surface-enhanced Raman spectroscopy (SERS), by incorporatingsingle-walled carbon nanotubes (SWCNTs) as an SERS probe within themetasurfaces. Our disordered plasmonic system, generated by a bottom-upprocess, offers excellent performance and compatibility with efficientphotothermal conversion. Moreover, it also provides a novel platformfor various hot-electron and energy-harvesting functionalities.</p>