Large-area flexible thermal control films via balancing low solar absorptivity and low infrared emissivity

Traditional thermal control coatings, with low solar absorptivity and high infrared emissivity, have limited suitability for celestial bodies like Venus, Mercury, and the Moon, which experience intense solar irradiation and extreme diurnal thermal fluctuations. This study proposes a groundbreaking evaluation metric specifically tailored for deep space exploration environments and develops innovative large-area flexible low-absorption low-emission thermal control films (LALE TCFs). The film system structure of LALE TCFs is designed based on optical transfer matrix method (TMM), assembled by stacking polyimide, silver metal, and one-dimensional photonic crystal components. By combining the optical properties of the materials with light interference effects, this design achieves remarkably low solar absorptivity (α_S = 0.048) and low infrared emissivity (ε_IR = 0.08), demonstrating exceptional broadband reflection capabilities (R_{0.25-25 μm} = 0.96). The absorption–emission ratio (α_S/ε_IR = 0.6) can be precisely adjusted to lower the equilibrium temperature, while the optical characteristics of the LALE TCFs exhibit stability during UV exposure (500 ESH) and extreme temperature (−196–200 °C) tests. This advanced thermal regulation technology enables large-scale mass production, offering a paradigm-shifting solution for next-generation deep space exploration missions.