The present invention relates to organic electroluminescent devices including one or more light-emitting layers B, each of which is composed of one or more sublayers including as a whole one or more excitation energy transfer components EET-1, one or more excitation energy transfer components EET-2, and one or more small full width at half maximum (FWHM) emitters S.sup.B emitting light with an FWHM of less than or equal to 0.25 eV. Furthermore, the present invention relates to a method for generating light by means of an organic electroluminescent device according to the present invention.

The present invention relates to an organic electroluminescent device including at least one light-emitting layer B composed of one or more sublayers, wherein the one or more sublayers of the light-emitting layer B as a whole include at least one host material H.sup.B, at least one phosphorescence material P.sup.B, at least one small FWHM emitter S.sup.B, and optionally at least one TADF material E.sup.B, wherein S.sup.B emits light with a full width at half maximum (FWHM) of less than or equal to 0.25 eV.

The present invention relates to an organic electroluminescent device including at least one light-emitting layer B composed of one or more sublayers, wherein the one or more sublayers of the light-emitting layer B as a whole include at least one host material H.sup.B, at least one phosphorescence material P.sup.B, at least one small FWHM emitter S.sup.B, and optionally at least one TADF material E.sup.B, wherein S.sup.B emits light with a full width at half maximum (FWHM) of less than or equal to 0.25 eV.

The embodiments of the disclosure provide an organic electroluminescent device, including an anode, a cathode, an emitting layer arranged between the anode and the cathode, and an assistant luminescent layer located on one side, facing the anode, of the emitting layer. The assistant luminescent layer includes a first host material and a first fluorescent guest material. The emitting layer includes a second host material, a TADF material, and a second fluorescent guest material. The first host material and the first fluorescent guest material satisfy: S1(B)−T1(B)>0.2 eV; S1(B)>S1(C); T1(B)>T1(C); ∥HOMO(B)−LUMO(C)|−S1(C)|≤0.2 eV. The lowest singlet state energy of the first host material is S1(B), and the lowest triplet state energy is T1(B). The lowest singlet state energy of the first fluorescent guest material is S1(C), and the lowest triplet state energy is T1(C).

A multicolor light-emitting element using fluorescence and phosphorescence, which has a small number of manufacturing steps owing to a relatively small number of layers to be formed and is advantageous for practical application can be provided. In addition, a multicolor light-emitting element using fluorescence and phosphorescence, which has favorable emission efficiency is provided. A light-emitting element which includes a light-emitting layer having a stacked-layer structure of a first light-emitting layer exhibiting light emission from a first exciplex and a second light-emitting layer exhibiting phosphorescence is provided.

A green phosphorescent light-emitting device with a long lifetime is provided. The light-emitting device includes a first electrode, a second electrode, and a light-emitting layer. The light-emitting layer is between the first electrode and the second electrode. The light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent light-emitting substance. The first organic compound includes a heteroaromatic ring skeleton and an aromatic hydrocarbon group. The second organic compound includes a bicarbazole skeleton. The lowest triplet excited level of the first organic compound is derived from only the aromatic hydrocarbon group. The energy of the lowest triplet excited level of the second organic compound is higher than or equal to 2.20 eV and lower than or equal to 2.65 eV.

A multicolor light-emitting element using fluorescence and phosphorescence, which has a small number of manufacturing steps owing to a relatively small number of layers to be formed and is advantageous for practical application can be provided. In addition, a multicolor light-emitting element using fluorescence and phosphorescence, which has favorable emission efficiency is provided. A light-emitting element which includes a light-emitting layer having a stacked-layer structure of a first light-emitting layer exhibiting light emission from a first exciplex and a second light-emitting layer exhibiting phosphorescence is provided.

Embodiments provide a light emitting device that includes a first electrode, a second electrode facing the first electrode, and at least one functional layer disposed between the first electrode and the second electrode. The at least one functional layer includes: a first compound represented by Formula 1; and at least one of a second compound represented by Formula HT or a third compound represented by Formula ET, wherein Formula 1, Formula HT, and Formula ET are each explained in the specification. The light emitting device exhibits low voltage, high efficiency, and long service life characteristics.

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Cyclometallated iridium complexes having triphenylene or aza triphenylene and bulky alkyl substitution that can be used as emitters in OLEDs to improve the external quantum efficiency (EQE) and lifetime of OLEDs are disclosed.

A multicolor light-emitting element using fluorescence and phosphorescence, which has a small number of manufacturing steps owing to a relatively small number of layers to be formed and is advantageous for practical application can be provided. In addition, a multicolor light-emitting element using fluorescence and phosphorescence, which has favorable emission efficiency is provided. A light-emitting element which includes a light-emitting layer having a stacked-layer structure of a first light-emitting layer exhibiting light emission from a first exciplex and a second light-emitting layer exhibiting phosphorescence is provided.