Prospects of chemically deposited metal chalcogenide thin films for solar control applications

Solar control coatings, required for architectural glazing applications in warm climates, must provide controlled optical transmission ( approximately 10-50%) of the solar radiation in the visible region and should reflect efficiently in the infrared (>0.7 mu m) region to create a cool interior in the buildings. Thin films of PbS and Cu_xS on glass substrates, deposited from chemical baths, are shown to possess excellent solar control characteristics-superior or comparable to the metallic solar control coatings. For example, for an acceptable range of integrated optical transmittance ( approximately 10-20%) in the visible region, the integrated infrared reflectance for AM2 solar spectrum for the different glazings are: PbS coated glass, 50%; Cu_xS coated glass, 14%; stainless steel/Cu coated glass, 25% and tinted glass, 4%. The Cu_xS and PbS coatings also have the advantage of giving pleasant reflected colours (golden, purple, blue, etc), which improves the cosmetic appearance. This paper presents the basic requirements of solar control coatings and provides a comparison of the characteristics of PbS and Cu_xS coatings against commercially available coatings.