Patent ID: 9112173
Filing Date: 2015-08-18
Classification: H01L

Abstract:
1. A light-emitting device comprising: an anode; a cathode; a phosphorescent layer and a fluorescent layer that are provided between the anode and the cathode and emit phosphorescent light and fluorescent light, respectively, upon energization of the anode and the cathode; an intermediate layer provided between the phosphorescent layer and the fluorescent layer; an electron transport layer provided between the fluorescent layer and the cathode; a hole blocking layer provided between the fluorescent layer and the electron transport layer; the intermediate layer includes a hole transport layer and an electron transport layer that are in contact with each other, the electron transport layer of the intermediate layer being located on the anode side, the hole transport layer of the intermediate layer being located on the cathode side, the intermediate layer suppressing transfer of triplet energy of the phosphorescent layer toward the fluorescent layer, and the intermediate layer permitting smooth transport of electrons and holes, wherein the intermediate layer does not emit light upon energization of the anode and the cathode and the light-emitting device having an increased relative current efficiency between 0.95 to 1.52 while suppresses an increase in drive voltage for the light-emitting device.