SOLAR CONTROL CHARACTERISTICS OF CHEMICALLY DEPOSITED LEAD SULFIDE COATINGS

Chemically deposited lead sulfide thin films on glass substrates are found to satisfy the basic requirements for solar control coatings for window glazing applications in warm climates, where a low transmittance (∼10%-30%) in the visible region is to be coupled with an appreciable reflectance for infrared radiation. The depositions were made on glass substrates from alkaline/ ammoniacal baths of lead acetate, thiourea and small amounts of triethanolamine. The coating can produce a gray, purple or bluish appearance in reflected daylight with near normal specular reflectance (visible region) of ∼15%-25%. These coatings appear yellowish in transmitted daylight with 7%-25% transmittance, depending on the duration of deposition. The integrated infrared (0.70 to 2.5 μm) reflectance for air mass (AM) 2 solar spectrum of typical PbS coated glass is ∼37% as compared to ∼7% for the uncoated glass. The advantages of chemical deposition for large area coatings, the desirable features of PbS as a solar control coating, and toxicity considerations are discussed. © 1990.