Multiband Light Absorption Hydrogel with Adjustable Light Transmission for Smart Window

Area of Science:

• Materials Science
• Nanotechnology
• Sustainable Energy

Background:

• Thermochromic smart windows regulate sunlight to control indoor temperatures.
• Existing materials struggle to effectively absorb the near-infrared (NIR) spectrum, a primary heat source.
• Upconversion nanoparticles (UCNPs) offer potential for enhanced light modulation.

Purpose of the Study:

• To optimize NIR light modulation in thermochromic smart windows.
• To develop a novel smart window material with improved solar spectral control.
• To enhance indoor brightness by converting NIR to visible light.

Main Methods:

• Incorporation of upconversion nanoparticles (UCNPs) into a poly(N-isopropylacrylamide) (PNIPAm) matrix.
• Fabrication of a microcrystalline composite hydrogel.
• Testing of solar spectral modulation performance and temperature regulation.

Main Results:

• The composite hydrogel demonstrated significant reduction in visible light transmittance (80.1% to 34.7%) upon temperature-induced phase transition.
• The smart window achieved a 23 °C temperature drop compared to standard glass.
• Effective blocking of NIR solar radiation was observed.

Conclusions:

• The UCNP-PNIPAm composite hydrogel offers a novel approach for thermochromic smart windows.
• This material exhibits broadband solar spectrum modulation and excellent durability.
• The developed smart windows enhance energy efficiency by suppressing indoor temperature increases.