Electrochemically-Tunable Intersubband Plasmon Absorption in Carbon Nanotube Films

Owing to their unique photophysics and highly tunable electronic properties, carbon nanotubes (CNTs) are promising materials for next-generation electrochromic devices. Here, we present recent work on ionic liquid-gated carbon nanotube devices that show reversible, bistable, and tunable absorption of near-infrared (NIR) radiation. Gating of the CNTs enables reversible changes in the optical transmittance of up to 40% in the wavelength range of 1.7 – 2.2 µm. Additionally, these devices exhibit bistability in an open-circuit configuration that persists for hundreds of seconds. We explore—both experimentally and with numerical modelling—the impact of CNT diameter on the absorption spectrum and the electrochemical properties of the devices. Our results have implications for the use of CNTs in electrochromic, charge storage, and chemical sensing applications.