Electrochemically Active Metasurfaces

Electrochemistry is a powerful tuning knob for inducing drastic material property change. By applying an electrical bias while using counterions to maintain charge neutrality, electrochemistry can vary the carrier density or even trigger a phase transformation in an electrically addressable manner. Electrochemistry is an ideal tool in many applications where tunable range, scalability, or non-volatility is crucial. However, electrochemically active metasurfaces are still largely underexplored, probably due to the lack of a property database to perform metasurface design and optimization. More co-development is needed among fundamental materials science, metasurface design, and electrochemical device engineering. In this talk, I will present two examples of electrochemically active metasurfaces. (i) Conducting polymer near-perfect dynamic thermal emitter. We conducted infrared ellipsometry to measure the potential-dependent optical property and designed a tunable MIM near-perfect absorber for wearable variable emittance (WeaVE) devices for personal thermoregulation. (ii) Reversible metal electrodeposition for active beam steering metasurface. Because reversible electrodeposition can create and dissolve metals on demand, active metasurface can be achieved by creating and dissolving the meta-atoms or affecting the periodicity. As a proof of concept, we will demonstrate a reflection-type beam steering metasurface based on this principle and discuss the outlook and future challenges and opportunities.