Multilayer optical filter for energy-efficient smart-window applications

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Smart windows require advanced optical filters for energy efficiency.
• Passive solar control is crucial for reducing building energy consumption.
• Multilayer dielectric filters offer tunable optical properties.

Purpose of the Study:

• To propose and theoretically investigate a spectrally engineered broadband optical short-wave-pass (OSWP) multilayer filter.
• To evaluate the filter's performance for passive smart-window applications.
• To demonstrate the potential for reducing solar heat gain in energy-efficient glazing.

Main Methods:

• Theoretical investigation using the transfer matrix method (TMM).
• Design of a cascaded dielectric multilayer architecture (SiOF, Si3N4, BaSnO3).
• Simulation of optical response across visible and near-infrared (NIR) spectral regions.

Main Results:

• The proposed design achieves high visible-light transmittance and broadband NIR rejection.
• Simulated spectra show a well-defined photonic band gap with sharp spectral selectivity.
• Calculated solar heat gain coefficient is approximately 0.37, indicating favorable solar-control performance.
• Angular analysis reveals tunable photonic band gap with incidence angle.

Conclusions:

• The proposed multilayer platform shows potential as a passive optical coating for smart windows.
• The filter can improve solar control and reduce solar heat gain in buildings.
• The design offers efficient suppression of infrared wavelengths while preserving daylight transmission.