Inherent Photoluminescence-Enhanced Daytime Radiative Cooling by Highly Crystalline Cellulose Films

Area of Science:

• Materials Science
• Sustainable Energy
• Optics

Background:

• High-temperature weather necessitates advanced passive daytime radiative cooling (PDRC) materials.
• Natural cellulose offers sustainable potential for PDRC due to its structure.
• Improving PDRC in regenerated cellulose materials remains a challenge.

Purpose of the Study:

• To investigate the impact of high crystal structure on regenerated cellulose film PDRC performance.
• To explore the role of photoluminescence (PL) in enhancing PDRC through photon conversion.
• To develop high-performance PDRC materials from regenerated cellulose for energy conservation.

Main Methods:

• Fabrication of regenerated cellulose films with varying crystallinity.
• Characterization of photoluminescence (PL) properties.
• Measurement of optical reflectivity across the 0.3-2.5 μm waveband.
• Evaluation of cooling power under simulated solar irradiation.

Main Results:

• High crystallinity in regenerated cellulose films enhances photoluminescence (PL) capacity.
• PL behavior improves PDRC via photon conversion, shifting UV to visible light emission.
• The cellulose film achieved 93.48% average reflectivity (0.3-2.5 μm), a 4.79% increase.
• Cooling power increased by 115.9% due to PL enhancement.

Conclusions:

• Highly crystalline regenerated cellulose films exhibit significantly improved PDRC performance.
• Intrinsic photoluminescence is a key mechanism for enhancing radiative cooling.
• These materials show promise for sustainable energy conservation in urban environments.