Radiative Cooling Droplet‐Electricity Generator for Energy‐Saving Houses

Abstract Rising energy costs and depleting fossil fuel reserves necessitate integrating multiple energy‐harvesting technologies in energy‐saving houses to reduce carbon footprints. Unlike photovoltaics or wind generators, droplet‐electricity generators (DEGs) can operate in rainy conditions, thereby complementing existing renewables in energy‐saving houses. However, inadequate thermal management in traditional DEGs restricts their practical applicability. To overcome this limitation and enhance year‐round energy efficiency, this work proposes a radiative cooling droplet‐electricity generator (RC‐DEG) combining raindrop energy harvesting with passive radiative cooling for efficient energy savings. This is achieved with a radiative triboelectric layer (RTL) comprising polydimethylsiloxane (PDMS)/titanium dioxide (TiO₂) composite and a porous polytetrafluoroethylene (PTFE) layer. As the DEG component, porous PTFE enhances triboelectric properties, while the PDMS/TiO₂ composite (dielectric constant 3.3) improves charge storage and electricity output performance during rainfall. For optimized radiative cooling parts, the binary TiO₂ particles (200 and 400 nm) in the PDMS matrix increase average reflectivity (92.9%) and also obtain high infrared emissivity (94.8%), yielding a temperature reduction of ≈6.8 °C below ambient temperature under solar irradiance (≈709 W m − 2 ). This work introduces an effective synergistic energy solution operating under all‐weather conditions in energy‐saving houses, advancing both energy conversion and thermal management for sustainable technologies in future smart cities.