Long-Term Stable Thermal Emission Modulator Based on Single-Walled Carbon Nanotubes

Dynamic control of a material's thermal emission could enable many emerging applications, such as thermal camouflage and infrared (IR) display. Low-dimensional carbon nanomaterials have shown great potential in these applications because of their tuneability in charge density via static gating or ionic intercalation. Herein, a thermal emission modulator based on single-walled carbon nanotubes (SWCNTs) is realized by ionic gating. The Fermi energy of the SWCNTs is shifted via the adsorption of ions on the surface, and the highest emissivity is observed at the neutral state while both P-type and N-type SWCNTs have a reduced emissivity. An emissivity modulation range is achieved approximately from 0.45 to 0.95 within the electrochemical window of the used ionic liquid. Thermal camouflage and IR display applications are then demonstrated by utilizing the tuneable thermal emissivity of the fabricated SWNCT films. More importantly, a single-layer structure allows effective dynamic control purely by static gating, without involving any ion interaction process that may cause structural damage, as observed in graphene and multi-walled nanotubes. Therefore, the SWCNT-based IR modulators exhibit long-term stability, with nearly identical modulation range and response time after 6000 dynamic tuning cycles, indicating great potential for practical applications.