Patent ID: 6475648
Filing Date: 2002-11-05
Classification: H01B,H01L,Y10S

Abstract:
An organic luminescent layer for use in an electroluminescent device with improved operating life, comprising:a) an organic host material capable of sustaining both hole and electron injection and recombination wherein the host material includes Alq; and â€ƒand b) at least three dopants: i) a first dopant capable of accepting energy of electron hole combination in the host material; ii) a second dopant capable of trapping the holes from the host material; and iii) a third dopant capable of accepting energy from the electron hole combination in the host material and accepting energy transferred from the second dopant; c) the first dopant being selected so that the bandgap energy of the first dopant is less than the bandgap energy of the host material; and d) the second dopant being selected to have a hole trapping energy level above the valence band of the host material; and e) the third dopant having a bandgap energy less than the bandgap energy of the first dopant.