Patent ID: 9142710
Filing Date: 2015-09-22
Classification: H01L

Abstract:
1. A light-emitting device comprising: an anode; a first light-emitting layer over the anode, the first light-emitting layer comprising a first phosphorescent compound and a first host material; a second light-emitting layer between the anode and the first light-emitting layer and in contact with the first light-emitting layer, the second light-emitting layer comprising a second phosphorescent compound, a first electron-transport compound, and a first hole-transport compound; and a cathode over the first light-emitting layer, wherein an emission wavelength of the second phosphorescent compound is longer than an emission wavelength of the first phosphorescent compound, wherein a triplet excitation energy of the first host material is higher than or equal to a triplet excitation energy of the first electron-transport compound or the first hole-transport compound, wherein the first electron-transport compound and the first hole-transport compound form an exciplex, and wherein a difference in energy between an emission peak wavelength of the exciplex and a peak wavelength of an absorption band of the second phosphorescent compound which originates from a triplet metal to ligand charge transfer transition, is 0.2 eV or less.