A light-emitting element including a fluorescent material as a light-emitting material and having high emission efficiency is provided. The light-emitting element includes a pair of electrodes and an EL layer provided between the pair of electrodes. The EL layer includes a host material and a guest material. The host material is capable of exhibiting thermally activated delayed fluorescence at room temperature. The guest material is capable of exhibiting fluorescence. The second triplet excitation energy level of the guest material is higher than or equal to the lowest singlet excitation energy level of the guest material.

The present invention relates to organic electroluminescent devices comprising a light-emitting layer B comprising a host material H.sup.B, a first thermally activated delayed fluorescence (TADF) material E.sup.B, and a depopulation agent S.sup.B.

An organic electroluminescence device, a preparation method thereof, and a display apparatus, the organic electroluminescence device including an organic light emitting layer which includes a host material, a sensitizer material, and a resonance thermally activated delayed fluorescent material, where the host material is a wide bandgap material, and the sensitizer material is a thermally activated delayed fluorescent material. The singlet state energy level of the thermally activated delayed fluorescent material falls between the singlet state energy level of the wide bandgap material and the singlet state energy level of the resonance thermally activated delayed fluorescent material. The triplet state energy level of the thermally activated delayed fluorescent material falls between the triplet state energy level of the wide bandgap material and the triplet state energy level of the resonance thermally activated delayed fluorescent material.

Discussed is an organic compound of Formula 1 and an organic light emitting diode and an OLED device including the organic compound. In the organic compound, Ar1 is a heteroaryl group comprising a nitrogen atom, and Ar2 is a C.sub.6 to C.sub.30 aryl group, and R is a C.sub.1 to C.sub.10 alkyl group. The organic compound may be included in an emitting material layer of the organic light emitting diode as a host such that an emitting efficiency and a lifespan of the organic light emitting diode and the OLED device are improved. ##STR00001##

A condensed cyclic compound represented by Formula 1 and an organic light-emitting device including the same: ##STR00001##
wherein, in Formulae 1, Y.sub.11 is a group represented by Formulae 2-1 to 2-3 and Y.sub.12 is a group represented by Formulae 3-1 to 3-5, 4-1, or 4-2 as described herein.

The present invention provides an organic electroluminescent device, a display panel, and a display device. An organic electroluminescent device, including: an anode and a cathode, arranged in opposite; a light-emitting layer, between the anode and the cathode; a first auxiliary function layer, between the light-emitting layer and the anode; and a second auxiliary function layer, between the light-emitting layer and the cathode; where the light-emitting layer comprises a first compound, a second compound and a third compound; a Stokes shift between an absorption spectrum of the second compound and an emission spectrum of the second compound is smaller than 70 nm; and a doping mass ratio of the second compound in the light-emitting layer is smaller than 50 wt %.

A compound is represented by a formula (1) below, in which k is an integer of 0 or more, m is an integer of 1 or more, n is an integer of 2 or more. L is a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 30 ring carbon atoms, CN is a cyano group, and D.sub.1 and D.sub.2 are each independently represented by one of a formula (2), a formula (3) and formula (3x) below, D.sub.1 and D.sub.2 being optionally mutually the same or different.

##STR00001##

Provided are an organic electroluminescent material and a device thereof. The organic electroluminescent material includes a metal M and at least one C{circumflex over ( )}N bidentate ligand L.sub.a coordinated with the metal M, the maximum emission wavelength of the photoluminescence spectrum of the organic electroluminescent material at room temperature is greater than or equal to 410 nm and less than or equal to 700 nm, and the emission spectrum area ratio of the organic electroluminescent material is less than or equal to 0.145. The metal complex has significant advantages in organic electroluminescent devices, in particular the improvement of device efficiency. Further provided are an organic electroluminescent device including the metal complex and a compound composition including the metal complex.

One object of this invention is to provide a novel light-emitting device with low power consumption. The light-emitting device includes a first light-emitting element and a second light-emitting element. The first light-emitting element includes a first electrode, a second electrode, and a light-emitting layer. The second light-emitting element includes the first electrode, a third electrode, and the light-emitting layer. The second electrode comprises only a first conductive film, and the third electrode comprises a second conductive film and a third conductive film. The first electrode has a function of reflecting light. The second conductive film has functions of reflecting light and transmitting light. The first conductive film and the third conductive film each have a function of transmitting light.

A reliable light-emitting element with low driving voltage is provided. The light-emitting element includes an electron-injection layer between a cathode and a light-emitting layer. The electron-injection layer is a mixed film of a transition metal and an organic compound having an unshared electron pair. An atom of the transition metal and the organic compound form SOMO.