Visible transparent, infrared stealthy polymeric films with nanocoating of ITO@MXene enable efficient passive radiative heating and solar/electric thermal conversion

Visible transparent yet low infrared-emissivity (ε) polymeric materials are highly anticipated in many applications, whereas the fabrication of which remains a formidable challenge. Herein, visible transparent, flexible, and low-ε polymeric films were fabricated by nanocoating decoration of indium tin oxide (ITO) and MXene on polyethylene terephthalate (PET) film surface through magnetron sputtering and spray coating, respectively. The obtained PET-ITO@MXene (PET-IM) film exhibits low ε of 24.7% and high visible transmittance exceeding 50%, endowing it with excellent visible transparent infrared stealthy by reducing human skin radiation temperature from 32 to 20.8 °C, and remarkable zero-energy passive radiative heating capability (5.7 °C). Meanwhile, the transparent low-ε PET-IM film has high solar absorptivity and electrical conductivity, enabling superior solar/electric to thermal conversion performance. Notably, the three heating modes of passive radiative and active solar/electric can be integrated together to cope with complex heating scenarios. These visible transparent low-ε polymeric films are highly promising in infrared stealth, building daylighting and thermal management, and personal precision heating.