Smart windows switch on the light

Optical switching devices for regulating incident solar energy that can replace traditional windows in buildings, vehicles, and aircraft are discussed. The chromogenic material in these smart windows exhibits a large change in optical properties with variation in applied electrical field, charge, light intensity, spectral composition, or temperature. The optical change transforms the material from a highly transmitting state to a partly reflecting (or absorbing) state over all or part of the visible and solar spectra. The optical switching can be activated electrically or nonelectrically. Electrically activated types, including electrochromic, liquid-crystal, and dispersed-particle (electrophoretic) devices, as well as devices based on reversible electrodeposition, and nonelectrically activated types, including devices based on photochromic and thermochromic materials, are described.<
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