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A Paintable Bioinspired Stratified Skin Resolving the Cooling-Electricity Trade-Off for All-Weather Building
Yijun Zeng1,2, Yuxin Song2, Jingjing Wang2
1Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China.
Advanced Materials (Deerfield Beach, Fla.)
|June 13, 2026
Summary
This study introduces a paintable skin for passive daytime radiative cooling (PDRC) that also generates electricity from rainfall using a droplet electricity generator (DEG). This innovation enhances cooling performance and expands the benefits of PDRC across diverse weather conditions and latitudes.
Area of Science:
- Materials Science
- Energy Harvesting
- Sustainable Building Technologies
Background:
- Passive daytime radiative cooling (PDRC) mitigates heat stress by radiating heat to space but is limited by rainfall and high-latitude overcooling.
- Droplet electricity generators (DEGs) can harness rainfall for power, but integrating them with PDRC while maintaining performance is difficult.
Purpose of the Study:
- To develop a paintable, bifunctional skin that integrates PDRC and DEG functionalities, overcoming limitations of standalone systems.
- To achieve both efficient radiative cooling and electricity generation from rainfall in a single material system.
Main Methods:
- Inspired by Tillandsia trichomes, a stratified skin was engineered with a fluorinated top layer for cooling and electrification, and nanoparticle layers for solar scattering and dielectric charge storage.
- Monte Carlo simulations guided the material design for optimized optical properties and performance evaluation.
- Outdoor cooling performance and electrical power generation during simulated rainfall were measured.
Main Results:
- The bifunctional skin achieved 96.2% solar reflectance and 96.5% thermal emissivity.
- It delivered a peak net cooling power of 104 W m⁻² and sustained outdoor sub-ambient cooling up to 9.5°C for over six months.
- During rainfall, a peak electrical power density of 357 W m⁻² was achieved.
Conclusions:
- The developed paintable skin effectively integrates PDRC and DEG, offering a scalable solution for all-weather building retrofits.
- Global modeling indicates a 33.9% increase in the latitude span benefiting from this technology compared to PDRC alone.
- This technology provides latitude-robust, weather-resilient cooling and power generation for buildings.
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