As one of the most promising next generation low cost full color flat panel displays organic light emitting devices (OLEDs). (OLEDs) are synthesized by light emitting organic metal complexes. The light emitting have wide range of applications in electronic materials in current time.The most critical performance characteristic for OLEDs is the device operational lifetime. OLEDs have achieved long operational stabilities through the organic materials using (a) photoluminescent with high quantum yield, (b) chemically and thermally stable and (c) tuning the compounds so that good sublimable properties can be obtained. The advantages of using organic materials over inorganic materials are their excellent color gamut with good light fluorescence efficiency. This book may serve for the undergraduate and postgraduate students and will work as good reference for the researchers, professionals interested in the field of Photoluminescent Studies.