Active Plasmonic Surfaces via Electrically Driven Actuation of DNA-Tethered Nanoparticles.

Nanoparticle-on-mirror (NPoM) plasmonic surfaces (PSs) exhibit a rich ensemble of interesting optical properties, including strong field enhancement and vivid structural colors. NPoMs can be easily fabricated via the drop-casting method, and their optical responses can be tailored by, for example, the size, morphology, and material composition of the nanoparticles and/or the thickness of the spacer layer between the nanoparticles and the metal film. Despite the ease of fabrication, implementing active modulation of optical responses in NPoM PSs has remained challenging. Here, we demonstrate the realization of electrically driven NPoM active plasmonic surfaces (eNPoM). Electric potentials are used to modulate the distance between the DNA-tethered metal nanoparticles and the metal film, which leads to a strong change in the optical response. Our eNPoM displays large reflectance modulation in the visible spectral range at frequencies beyond 1 kHz. Moreover, our fabrication process can be combined with standard lithography methods to arrange nanoparticles at predefined locations while retaining functionality. These results provide an approach to lithography-complementary fabrication of active plasmonic surfaces with strong and reversible modulation of optical responses.