In3SbTe2-based all-season smart film with synergistic modulation of solar and thermal radiation

The reversible transformation of radiative cooling and solar heating of the film is significant for a building's energy conservation and carbon emission reduction. The current technology is constrained by its reliance on complex control mechanisms and a narrow control scope, which collectively impede its practical deployment. In this Letter, we introduce an all-season smart film, a multilayer film composed of In3SbTe2 (IST), CaF2, and ZnS on an Al substrate, which possesses the unique ability to synergistically modulate solar-thermal radiation. The solar absorptance and infrared emittance are (anormal, εnormal) = (0.829, 0.055) for the solar heating mode and (0.361, 0.835) for the radiative cooling mode, respectively. The underlying mechanism pertains to the Fabry–Pérot resonance and antireflection. The modulation property of the smart film remains excellent even when the incident angle is large. Furthermore, the smart film is capable of achieving multilevel modulation through the alteration of the crystalline IST percentage. The excellent modulation properties of the smart film are substantiated through a quantitative assessment of the net heat flux for terrestrial applications. This analysis reveals that the smart film with amorphous IST achieves a solar heating flux of 800 W/m2 at 250 K, while for crystalline IST it exhibits a radiative cooling flux of 600 W/m2 at 330 K. Such a simple multilayer structure can be easily fabricated, which would facilitate the advancement and practical implementation of an all-season smart film.