CPC H01L 51/0074 (2013.01) [H01L 51/006 (2013.01); H01L 51/0061 (2013.01); H01L 51/0072 (2013.01); H01L 51/0085 (2013.01); H01L 51/5004 (2013.01); H01L 51/5016 (2013.01); H01L 51/5056 (2013.01); H01L 51/0052 (2013.01); H01L 51/5072 (2013.01); H01L 2251/5384 (2013.01); H01L 2251/552 (2013.01)] | 16 Claims |
1. A light-emitting device comprising:
a hole-transport layer and a light-emitting layer between a pair of electrodes,
wherein the light-emitting layer includes a first organic compound, a second organic compound, and a third organic compound that converts triplet excitation energy into light emission,
wherein a combination of the first organic compound and the second organic compound forms an exciplex,
wherein a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound,
wherein a LUMO level of the first organic compound is lower than a LUMO level of the second organic compound,
wherein the hole-transport layer comprises a fourth organic compound whose HOMO level is higher than the HOMO level of the second organic compound,
wherein an emission spectrum of the exciplex overlaps with an absorption spectrum of the third organic compound,
wherein a difference between an energy value of a peak of the emission spectrum of the exciplex and an energy value of a peak of an absorption band on the lowest energy side of the absorption spectrum of the third organic compound is 0.2 eV or less, and
wherein the hole-transport layer is in contact with the light-emitting layer.
|