Optimization of optoelectronic characteristics of sintered cadmium sulphide photoconductive layers

Photograde cadmium sulphide useful for sintered polycrystalline cadmium sulphide photoconductive cells as also for solar cells can be prepared by a simple chemical reaction between a soluble cadmium salt and thiourea in an aqueous alkaline solution by optimizing the pH, temperature and concentration of the constituents in the bath. The precipitated cadmium-sulphide after drying at 1200C was found to result in a photograde quality of 99.999% pure cadmium sulphide as estimated by atomic absorption spectrophotometer. Details are given in this paper, of the process of preparation of CdS powder, screen printing and sintering the cadmium sulphide layers to give finally the photoconductive cell which gave on irradiation on a change in the resistance of six to seven orders. The sintering technique and the mechanism of the reaction resulting in high photosensitivity of the layer obtained are discussed in detail