Nano-science and nanotechnology has emerged as an interdisciplinary subject in true sense. Nanostructures show size and shape dependent characteristics. Ternary materials provide possibility of tailoring the properties as per the requirements. Combination of nanocrystals and polymers enhance the optical as well as mechanical behaviour of the composites. CdZnSe nanocrystals give narrow light emission peak with colour depending on the crystal size, where as these embedded in PVA matrix show intense broad electroluminescence spectra at low voltage with tailorable colour. These materials may be promising for various optoelectronic devices. We sincerely hope that the readers will find the content of this book useful for scientific as well as technological applications.