Widely Tunable Infrared Plasmonic Nanoantennas Using Directed Assembly

Infrared plasmonic nanoantennas are key building blocks in nanotechnology. By coupling and confining light into spatial volumes below the diffraction limit, infrared plasmonic nanoantennas provide unique opportunities to sense and signal at nanometer length scales for energy harvesting, as light sources, and in nanomedicine applications. However, in contrast to their radio‐ and microwave counterparts, widespread use of plasmonic nanoantennas has been limited, due in part to the inability to synthesize these structures maintaining nanoscale precision in large batches with uniform yields. This communication describes a directed assembly approach to generate large quantities of infrared plasmonic nanoantennas with sharp and widely tunable absorption peaks from 1 to 3 µm. It is experimentally demonstrated that the nanoantenna absorption peak depends linearly on the chain length, in agreement with simulations, providing a straightforward means to understand and predict the infrared response of these materials. A fabrication method for plasmonic nanoantennas is presented, which enables their production with nanoscale precision in large batches with uniform yields, overcoming previous limitations in the use of such antennas. The nanoantennas are self‐assembled using gold nanorods and molecular linkers, then irradiated with laser light welding the nanorods together, producing large, high‐quality yields of nanoantennas.