Smart Window with Reversible and Instantaneous Photoluminescence based on Microsphere Structure

Area of Science:

• Materials Science
• Optics
• Polymer Chemistry

Background:

• Smart windows dynamically regulate light transmittance, crucial for modern applications.
• Three-dimensional (3D) photonic crystal microspheres offer advanced functionalities for smart windows.
• Existing polymer microsphere smart windows suffer from poor mechanical strength and defects.

Purpose of the Study:

• To develop a robust and functional smart window overcoming limitations of previous polymer microsphere designs.
• To investigate the optical and mechanical properties of a novel microsphere-based smart window.

Main Methods:

• Fabrication of a smart window using tightly packed, cross-linked polymer microspheres containing organic photochromic dyes.
• Compression of the microsphere precursor under a high elastic state.
• Evaluation of photoluminescence, mechanical strength, and visible-light transparency.

Main Results:

• The smart window demonstrated rapid, reversible fluorescent photoluminescence without fatigue over 50 cycles upon ultraviolet (UV) excitation.
• The cross-linked network structure resulted in excellent mechanical strength (hardness of 0.158 GPa) and high visible-light transparency.
• A QR code was visible under visible light but obscured under UV light due to photoluminescence.

Conclusions:

• The developed microsphere-based smart window offers enhanced mechanical properties and tunable optical responses.
• The fabrication method provides a versatile strategy for creating advanced optical devices from amorphous polymers.
• This approach presents a simple, effective, and potentially economical method for smart window technology.