A light-emitting device includes: a first electrode; a second electrode facing the first electrode; an interlayer located between the first electrode and the second electrode and including an emission layer; and an electron transport region located between the emission layer and the second electrode and including: a hole blocking layer; and an electron transport layer, an electron injection layer, or any combination thereof, wherein the emission layer includes a first host, a second host, a first dopant, and a second dopant, and the electron transport region includes a layer including a red dopant compound.

A light-emitting device includes a first compound represented by Formula 1, for example, in an emission layer of the device as a dopant or emitter. An electronic apparatus includes the light-emitting device, and the first compound represented by Formula 1 is an organometallic compound, in which M is platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), silver (Ag), or copper (Cu):

##STR00001##

A display panel having a plurality of subpixels is provided. The display panel includes a base substrate; a plurality of light emitting elements on the base substrate; and a quantum dot layer on a side of the plurality of light emitting elements away from the base substrate. A respective one of the plurality of light emitting elements includes a first light emitting layer and a second light emitting layer sequentially stacked. The first light emitting layer is configured to emit a first light of a first wavelength range. The second light emitting layer is configured to emit a second light of a second wavelength range. The plurality of light emitting elements are configured to respectively emit a composite light. The quantum dot blocks of different colors are configured to respectively convert the composite light into light of different colors respectively in different subpixels.

Provided is a blue light emitting organic EL device having high emission efficiency and a long lifetime.

This organic EL device includes one or more light emitting layers between an anode and a cathode opposite to each other, wherein at least one of the light emitting layers has a difference between excited singlet energy (Si) and excited triplet energy (Ti) of 0.20 eV or less and includes a light emitting dopant represented by the following formula (5), a first host selected from biscarbazole compounds, and a second host selected from N-containing 6-membered ring compounds, wherein X.sup.3 is N—Ar.sup.4, O, or S and at least one X.sup.3 is N—Ar.sup.4.

##STR00001##

An OLED device comprises an anode and a cathode, and at least one graded emissive layer disposed between the anode and the cathode, the graded emissive layer comprising first and second materials, wherein a concentration of the first material increases continuously from an anode side of the graded emissive layer to a cathode side of the graded emissive layer, and a concentration of the second material decreases continuously from the anode side of the graded emissive layer to the cathode side of the graded emissive layer. An OLED device comprising a graded emissive layer and a hybrid white OLED device are also described.

A light-emitting element having high emission efficiency is provided.

The light-emitting element includes a first organic compound, a second organic compound, and a third organic compound. The first organic compound has a function of converting triplet excitation energy into light emission. The second organic compound is preferably a TADF material. The third organic compound is a fluorescent compound. Light emitted from the light-emitting element is obtained from the third organic compound. Triplet excitation energy in a light-emitting layer is transferred to the third organic compound by reverse intersystem crossing caused by the second organic compound or through the first organic compound.

To provide a light-emitting element with high emission efficiency and low driving voltage. The light-emitting element includes a guest material and a host material. A HOMO level of the guest material is higher than a HOMO level of the host material. An energy difference between the LUMO level and a HOMO level of the guest material is larger than an energy difference between the LUMO level and a HOMO level of the host material. The guest material has a function of converting triplet excitation energy into light emission. An energy difference between the LUMO level of the host material and the HOMO level of the guest material is larger than or equal to energy of light emission of the guest material.

A light emitting element, includes a first light emitting layer and a second light emitting layer sequentially stacked; and an intermediate layer between the first light emitting layer and the second light emitting layer, and being in direct contact with the first light emitting layer on one side and in direct contact with the second light emitting layer on another side. Each of the intermediate layer, the first light emitting layer, and the second light emitting layer includes a same host material. The intermediate layer is a non-light emitting layer, and is an undoped layer absent of a dopant for emitting light. The light emitting element is configured to emit a composite light including the first light of the first wavelength range and the second light of the second wavelength range. The first wavelength range includes wavelength longer than the second wavelength range.

An object of the present invention is to provide an organic electroluminescent element containing an organic layer interposed between an anode and a cathode, the organic layer containing at least one light emitting layer, wherein the at least one light emitting layer contains a π-conjugated compound having an electron donor portion and an electron acceptor portion in the molecule; the π-conjugated compound has a direction vector from an atom having a HOMO orbital in the electron donor portion to an electron cloud of the HOMO orbital, and a direction vector from an atom having a LUMO orbital in the electron acceptor portion to an electron cloud of the LUMO orbital, and the two direction vectors form an angle θ in the range of 90 to 180 degrees; and the π-conjugated compound has a plurality of the electron donor portions or a plurality of the electron acceptor portions.

Embodiments provide a condensed cyclic compound, a light-emitting device that includes the condensed cyclic compound, and an electronic apparatus that includes the light-emitting device. The light-emitting device includes a first electrode, a second electrode facing the first electrode, and an interlayer between the first electrode and the second electrode and including an emission layer, wherein the emission layer includes the condensed cyclic compound. The condensed cyclic compound is represented by Formula 1, which is explained in the specification:

##STR00001##