Energy-saving all-weather window based on selective filtering of solar spectral radiation.

Passive all-weather windows, capable of selectively transmitting visible and infrared solar radiation, could help in bringing down fossil-fuel energy consumption globally by reducing the carbon footprint of typical air-conditioning systems for buildings and motor vehicles. Here, we report on designing metal-insulator-metal thin-films for application in passive windows, optimized for different climatic conditions. We analyze designs comprising different noble metals as well as their relatively inexpensive alternatives. By finding an optimal choice of materials and thicknesses of the metal and dielectric layers, our lithography-free simple design can provide all-weather solutions for passive windows with desired visible and infrared transmission/blocking capability. Obtained theoretical results agree well with full-wave simulations. Thus, our proposed designs enable developing low-cost, ultra-thin (thickness: 47-85 nm), polarization-independent, angle-insensitive (up to 83 deg), and large-area-compatible passive windows with improved solar-radiation control for different weather/climatic conditions. The figure-of-merit calculation shows that the relatively inexpensive metals used in our passive glasses can outperform industry-standard commercial glasses and previously reported infrared-blocking plasmonic glasses.