Thermal Emmitance of Solar Energy Assisted Chemical Bath Deposited Cadmium Sulphide (CDS) Thin Films on Aluminium

The chemical bath deposition (CBD) method was used to deposit good quality thin films of cadmium sulphide (CdS) on aluminium at room temperature of 300k (270C) and deposition times ranging from 16hrs to 36hrs. The flat sample plate (8.2 x7.2 x0.1 cm2) were cleaned by polishing them using emery paper and gamma polishing alumina. The plates were polished with distilled water and dried in air before usage. Thermal emmitances of the plates were measured before and after deposition using an instrument called thermocouple potentiometer. These plates were also weighed before and after deposition with an electronic weigh balance to determine the mass of plates. Six beakers each containing 25cm3, 0.4M CdCl2. H2o, 16cm3, 0.2M EDTA as a complexing agent, 12cm3, 1.0M NaoH, 20cm3, 0.8M (NH2) 2 CS and 7.0cm3 by volume of distilled water. The average value for the thermal emmitance of the polished plates is 0.15 � 0.01 while that of the thermal emmitances of the coated plates varied from 0.151 to 0.176 depending on deposition time. The film thickness ranged from 2.38�m to 9.53�m depending on deposition time. The thermal emmitance value of the coated plates compare with those obtained for spectrally selective surface can be employed in solar energy applications such as heating of houses, solar incubators and drying of crops.