The ternary compound CdSxSe1-x is a highly photosensitive material, it is used in many practical application such as discrete and multi element photoresistors, in optical filters, signal memory devices, laser screens, LSI circuits, Infrared imaging devices, Optoelectronic switches, linear image sensor for digital facsimile page scanners, Electro photography, Image intensifiers and exposure meters. This book is based on electro optical studies of rare earth doped CdSxSe1-x films, which were deposited by a simple and cost effective Chemical Bath Deposition method in the form of thin films. A highly efficient photoluminescent emission was achieved by incorporating rare earths like Holmium and Neodymium at low temperature. wet chemical routes of preparation provides ample opportunity to control the size, shape and properties of the material. Particularly the ternary compound CdS-Se has been obtained with different morphologies and tunable band gaps by controlling the bath temperature, pH, solvents and bath composition. PG students Researchers in the field of materials science, nanomaterials, optoelectronics and thin film and solar cell technology will be benefited by this work.