A small-bundle single-wall carbon nanotube electrothermal film for smart windows

Abstract The incorporation of electrothermal films into smart windows has been of intense research interest in developing highly conductive transparent films. However, achieving a high optical transparency and exceptional electrothermal performance simultaneously remains a great challenge. We reported a transparent conductive single-wall carbon nanotube (SWCNT) film comprised of highly-crystalline and long SWCNTs in small bundles. The SWCNT film with an average bundle diameter of 7.1 nm had a low sheet resistance of 26 Ω/□ at a transmittance of 82%, and had a constant temperature of 102 °C at a low applied voltage of 20 V. Integrating this transparent heating film with thermochromic materials enabled the fabrication of a flexible smart window with thermally triggered dynamic transparency. The device has a broad reversible visible light transparency range (~ 78%) and excellent cycling stability.