The two ageing problems of an organic light emitting devices (OLED) displays such as intrinsic degradation and dark-spot degradation are discussed. Intrinsic degradation is a gradual decrease in luminance of the display phosphorus that occurs during operation and dark-spot degradation is characterized by circular non-emissive areas that gradually cover a pixel. The causes of these degradation is found to be the morphological instability of the organic layers made of organic materials from the diamine group. The OLED lifetimes is increased by doping the electroluminescent layer and not the HTL, which delivers a lifetime of 5000 hours at an initial luminance intensity. The degradation is decreased by doping of the HTL, introducing a CuPc buffer layer at the hole-injection contact, and using a mixed emitting layer of hole and electron transporting molecules.