Infrared radiation and materials interaction: Active, passive, transparent, and opaque coatings

Any object on the earth’s surface having its temperature around 28°C acts as a strong source of thermal infrared radiation emitting mostly in 3–30 μM range. Thus, such objects become a source of infrared radiation with emission range overlapping with solar spectra. This overlapping is more significant in the 3–5 μM range. As the temperature of the object increases, the reflection of the solar radiation becomes less important than the self-emitted energy of the object. Since the emission from the heated objects and solar radiations has different overlapping mechanisms in different wavelength bands, the regulation of these radiations will also require different coating materials. Infrared reflective and absorptive materials are being used extensively in architectural, plastic, paints and military, photovoltaic, electronic, textiles, energy savings, etc. This chapter describes the mechanism of infrared radiation regulation by various organic and inorganic materials and their applications as active, passive, and opaque coatings.