Patent ID: 7906897
Filing Date: 2011-03-15
Classification: C09K,H01L,H05B

Abstract:
1. An organic electroluminescent element comprising at least a positive hole transport layer, a light emitting layer and an electron transport layer between at least a pair of electrodes, wherein the light emitting layer contains therein at least two light emitting materials having different electron affinity (Ea values) or ionization potentials (Ip values) and emitting phosphorescence having the same color as each other, and among the two light emitting materials, a light emitting material having a larger Ea value or Ip value is contained at a higher density in a region of the light emitting layer in the vicinity of the positive hole transport layer, while a light emitting material having a smaller Ea value or Ip value is contained at a higher density in a region of the light emitting layer in the vicinity of the electron transport layer.