This book gives a detailed analysis on how white and red light can be obtained from a single nanophosphor made from europium (III) ion doped into zinc sulfide semiconductor. Complete optimization such as the role ofpH, effects of capping agent, dopant concentrations and post-synthesis processing under different ambient and temperature conditions have been dealt with in great details. The striking aspect of this work is that the phosphor is reproducible. This is the first time a single phosphor is reported to emit the two most desired colours of red and white light. Another remarkable characteristic of this phosphor is that it absorbs energy at the near-UV and blue spectral regions, which is where most of the InGaN-based LEDs emit photons with high efficacy. Therefore, this phosphor has the potentials of being used for the production of white light-emitting diodes for application in general illumination.