Transparent solid slippery coating for winter photothermal de-icing and summer thermal management

Ice accumulation severely threatens the reliable operation of outdoor optical windows. Existing research has mainly developed passive anti-icing strategies, such as superhydrophobic surfaces (SHS) and slippery liquid-infused porous surfaces (SLIPS), and active de-icing strategies, such as photothermal coatings. However, SHS may suffer from wetting-state transition under harsh icing conditions, while SLIPS are prone to failure due to lubricant depletion; active photothermal coatings based on broadband absorbers such as carbon-based materials and MXenes often sacrifice optical clarity. To address these bottlenecks, this paper reports a novel coating technology that integrates three functions: solid-state sliding, high transparency, and highly efficient photothermal properties. By designing a phenyl/methylsiloxane cross-linked network and free PDMS segments, a solid slippery property (sliding angle of 16°) without liquid lubrication is achieved. Distinct from broad-spectrum photothermal fillers, Cs_xWO₃ nanoparticles exhibit relatively weak absorption in the visible region compared with the near-infrared region, enabling efficient near-infrared photothermal conversion while maintaining high visible transparency, thereby achieving efficient photothermal conversion, with a surface temperature of 86.5 °C and an incident-solar-power-based apparent photothermal conversion efficiency of 42.6% under 1 sun illumination, while maintaining a visible light transmittance higher than 83%. The coating synergistically integrates passive anti-icing and active de-icing, achieving a low ice adhesion strength of 56.8 kPa. Under no illumination at −20 °C, the coating prolonged the icing delay time to 121 s. Under 1 kW/m² simulated solar irradiation, the ice-melting time on the Cs_xWO₃–20/PSO coating was shortened by 46.4% compared with blank glass. Moreover, the coating exhibits excellent mechanical durability (stable performance after 1000 friction cycles) and long-term chemical stability. Notably, benefiting from the near-infrared-selective absorption/shielding characteristics of Cs_xWO₃, the coating can reduce the transmission of solar heat radiation in summer, lowering the temperature inside a model house by 19.9 °C. This result demonstrates that the coating provides not only winter photothermal de-icing but also summer thermal-management capability. To the best of our knowledge, few reported transparent anti-icing coatings have simultaneously integrated liquid-lubricant-free solid slipperiness, low ice adhesion, near-infrared-selective photothermal de-icing, and summer thermal-management capability. It provides an all-weather solution for outdoor optical windows that require both high transparency and anti-icing performance, such as automotive autonomous driving optical sensors, UAV optoelectronic pods, and BIPV photovoltaic curtain walls.