Increasing photo-thermal efficiency of VO2-based devices using carbon nanotube thin-films

This paper reports the first study on the use of single-wall carbon nanotubes (SWNTs) to reduce the amount of photo-thermal energy required to induce the phase transition in vanadium dioxide (VO₂) thin film sensors. A SWNT thin-film prepared using vacuum filtration process was transferred onto a VO₂ thin film. Owing to the superior light-absorption properties of SWNT thin-films, energy from a red light laser (650 nm) was efficiently harvested and converted to heat, which was then transferred from SWNT to VO₂ to induce the phase transition. We have confirmed that the quality of the VO₂ film was unaltered during the SWNT coating process, nor by the SWNT coating itself. These results show that the integration of SWNT films is an effective way to increase the efficiency of VO₂-based optical sensing devices and could potentially enable triggering of the phase transition in VO₂ films at ambient conditions, which would make low-power VO₂-based non-volatile multifunctional memories a reality. In addition, by using sorted SWNTs with pre-defined chirality, VO₂ sensors with tunable wavelength response could also be readily achieved.