OPTICAL-PROPERTIES OF PBS-CUXS AND BI2S3-CUXS THIN-FILMS WITH REFERENCE TO SOLAR CONTROL AND SOLAR-ABSORBER APPLICATIONS

A systematic study of the optical transmittance, reflectance and absorptance characteristics of chemically deposited PbS-CuxS films and Bi2S3-CurS films on glass substrates in the solar spectral range of 0.35-2.5-mu-m is presented with an intention of describing the range of characteristics available with these glazings for solar control and solar absorber coating applications. In the case of solar control application, a PbS thin film deposition for approximately 1 h or a Bi2S3 thin film deposition for approximately 1 h 30 min at room temperature followed by a 2 h deposition of CuxS thin film at 50-degrees-C and subsequent air annealing at 150-degrees-C for 30 min has been found to offer a visible transmittance of 12.5%. This corresponds to a visible reflectance of 22% (greenish yellow) in the case of PbS-CuxS films and 15% (greenish) in the case of Bi2S3-CuxS films. The solar absorptance is < 80% in both cases for substrate side incidence, due to the high reflection losses of approximately 20%. For film side incidence, a solar absorptance of 87% combined with a thermal emittance of 0.46 has been obtained in PbS-CuxS films.