Thermoplasmonic Semitransparent Nanohole Electrodes.

Nonradiative decay of plasmons in metallic nanostructures offers unique means for light-to-heat conversion at the nanoscale. Typical thermoplasmonic systems utilize discrete particles, while metal nanohole arrays were instead considered suitable as heat sinks to reduce heating effects. By contrast, we show for the first time that under uniform broadband illumination (e.g., the sun) ultrathin plasmonic nanohole arrays can be highly competitive plasmonic heaters and provide significantly higher temperatures than analogous nanodisk arrays. Our plasmonic nanohole arrays also heat significantly more than nonstructured metal films, while simultaneously providing superior light transmission. Besides being efficient light-driven heat sources, these thin perforated gold films can simultaneously be used as electrodes. We used this feature to develop "plasmonic thermistors" for electrical monitoring of plasmon-induced temperature changes. The nanohole arrays provided temperature changes up to 7.5 K by simulated sunlight, which is very high compared to previously reported plasmonic systems under similar conditions (solar illumination and ambient conditions). Both temperatures and heating profiles quantitatively agree with combined optical and thermal simulations. Finally, we demonstrate the use of a thermoplasmonic nanohole electrode to power the first hybrid plasmonic ionic thermoelectric device, resulting in strong solar-induced heat gradients and corresponding thermoelectric voltages.