Scattering-Enhanced Light Extraction for Radiative Thermal Load Mitigation in Fluorescent Films

Area of Science:

• Materials Science
• Optics
• Thermodynamics

Background:

• Traditional absorptive pigments cause solar heating.
• Fluorescent colorants are limited by total internal reflection (TIR), trapping emitted photons.
• This trapping increases parasitic solar absorption and radiative thermal load.

Purpose of the Study:

• To develop a scattering-enhanced light extraction strategy for fluorescent films.
• To overcome the TIR limit and reduce radiative thermal load.
• To optimize nanoparticle concentration for maximum light extraction efficiency.

Main Methods:

• Sequential quadratic programming optimization model for radiative thermal load.
• Monte Carlo ray-tracing simulations for light extraction efficiency.
• Outdoor experiments to validate temperature reduction.

Main Results:

• Light extraction technology expands sub-ambient cooling chromaticity from 19.3% to 64.9%.
• An optimal 0.5 wt% TiO2 nanoparticle concentration achieved 85.9% light extraction efficiency.
• The 0.5 wt% TiO2 sample showed a 4.1°C temperature decrease compared to the control.

Conclusions:

• Scattering-enhanced light extraction significantly boosts fluorescent color cooling performance.
• The developed method is cost-effective and scalable compared to microtexturing.
• This approach offers a promising solution for passive radiative cooling applications.