Highly Transparent and Haze Passive Daytime Radiative Cooling Organosiloxane Coatings via a Controlled Microphase Separation Process

Transparent building envelopes are valued for ample natural daylight, yet they face issues of glare, privacy concerns, and excessive solar heat gain. Existing anti-glare or radiative cooling coatings typically either reduce visible transmittance or fail to combine high haze with high infrared emissivity. We have developed a room-temperature-curing FPHS coating composed of polyethoxysiloxane (PEOS), hydroxyl silicone oil, and 3,3,3-(trifluoropropyl)trimethoxysilane (TTMS). Utilizing in-situ nanoparticle formation and microphase separation technology, this coating achieves a visible light transmittance of 90.43%, a haze of 84.64%, and an emissivity of 94.06% within the 8-13 μm atmospheric window. These unique optical properties enable a maximum daytime temperature reduction of 14.6 °C, while the low-surface-energy surface ensures self-cleaning and dust-repellent properties. When coated onto photovoltaic panels, the FPHS coating reduces operational temperatures of photovoltaic modules, elevates short-circuit current, and improves overall power conversion efficiency. It delivers a scalable, zero-energy strategy to simultaneously realize glare suppression, privacy modulation, and passive radiative cooling for transparent building envelopes and optoelectronic devices.