Black tungsten selective optical coatings for photothermal solar energy conversion

(Received 1st February, accepted 18 April 1992)

Abstract
By pyrolytic decomposition of W(CO) ₆ in the presence of an oxygen bleed black tungsten solar selective coatings have been deposited on different substrates - quartz, silicon and stainless steel. Quartz substrates were used to check the opacity of the films deposited; the silicon substrates were used to study the possibility of obtaining low-resistance material when fully annealed and the steel substrates to study the properties of the films on substrates suitable for a large scale application. The films were obtained at a temperature of 400°C and further partially annealed in a reducing atmosphere. The dependence of the structure and chemical composition on the annealing temperature was studied, as well as reflectance measurements in the visible and in the infrared region.