Devices having multiple multicomponent emissive layers are provided, where each multicomponent EML includes at least three components. Each of the components in each EML is a host material or an emitter. The devices have improved color stability and relatively high luminance.

Embodiments of the disclosed subject matter provide a device including a micronozzle array having separate redundant groups of depositors that each include a delivery aperture disposed between two exhaust apertures. The device may include a first row of depositors of a first redundant group, each of which may be connected in parallel to first common delivery lines and first common exhaust lines. The device may include a second row of depositors of a second redundant group, each of which is connected in parallel to second common delivery and second common exhaust lines. The first row of depositors and the second row of depositors may operate independently from one another. The device may be disposed within a deposition chamber and in proximity of a substrate.

An organic electroluminescence element including an anode, a light-emitting layer, a functional layer, and a cathode stacked in this order. The light-emitting layer and the functional layer are in contact with each other. Hole mobility of the light-emitting layer is greater than electron mobility of the light-emitting layer. The electron mobility of the light-emitting layer is equal to or greater than an effective electron mobility of the functional layer. A highest occupied molecular orbital (HOMO) level of a first functional material included in the light-emitting layer is at least 0.4 eV greater than a HOMO level of a second functional material included in the functional layer.

Disclosed is a device that includes an emissive material or region including a host that is doped with a first material as an emitter that is an acceptor and a phosphorescent-capable second material as a sensitizer. The first material and the second material each has a first singlet state and a first triplet state. The first triplet state of the second material is not lower than the first triplet state of the first material. The second material transfers excitons to the first material and the excitons that transition to the first triplet state of the first material can be activated to the first singlet state of the first material through a thermal activation process.

Provided is a light-emitting element with high external quantum efficiency and a low drive voltage. The light-emitting element includes a light-emitting layer which contains a phosphorescent compound and a material exhibiting thermally activated delayed fluorescence between a pair of electrodes, wherein a peak of a fluorescence spectrum and/or a peak of a phosphorescence spectrum of the material exhibiting thermally activated delayed fluorescence overlap(s) with a lowest-energy-side absorption band in an absorption spectrum of the phosphorescent compound, and wherein the phosphorescent compound exhibits phosphorescence in the light-emitting layer by voltage application between the pair of electrodes.

To increase emission efficiency of a fluorescent light-emitting element by efficiently utilizing a triplet exciton generated in a light-emitting layer. The light-emitting layer of the light-emitting element includes at least a host material and a guest material. The triplet exciton generated from the host material in the light-emitting layer is changed to a singlet exciton by triplet-triplet annihilation (TTA). The guest material (fluorescent dopant) is made to emit light by energy transfer from the singlet exciton. Thus, the emission efficiency of the light-emitting element is improved.

Provided is a light-emitting element including a fluorescence-emitting material with high emission efficiency. The light-emitting element includes a pair of electrodes and an EL layer between the pair of electrodes. The EL layer includes a first organic compound, a second organic compound, and a guest material. The first organic compound has a function of emitting a thermally activated delayed fluorescence at room temperature. The guest material has a function of emitting fluorescence. A HOMO level of the first organic compound higher than or equal to a HOMO level of the second organic compound. A LUMO level of the first organic compound is lower than or equal to a LUMO level of the second organic compound.

An organic electroluminescent device and a display apparatus. The organic electroluminescent device includes a first electrode, a second electrode and an organic layer located between the first electrode and the second electrode. The organic layer includes a light-emitting layer. The light-emitting layer contains a host material, a thermally activated delayed fluorescence sensitizer and a fluorescent dye. The energy level relationship between the host material and the thermally activated delayed fluorescence sensitizer is LUMO.sub.host≥LUMO.sub.sensitizer, while HOMO.sub.sensitizer≥HOMO.sub.host.

A novel light-emitting device that is highly convenient, useful, or reliable is provided. The light-emitting device includes a first electrode, a second electrode, a unit, and a first layer. The second electrode includes a region overlapping with the first electrode. The unit includes a region positioned between the first electrode and the second electrode. The unit includes a second layer and a third layer. The second layer includes a region where the third layer is positioned between the second layer and the first electrode. The second layer contains a light-emitting material. The first layer includes a region positioned between the third layer and the first electrode. The first layer contains a material having an acceptor property and a first material. The first layer includes a first region and a second region. The first region includes a region positioned between the second region and the first electrode. The first region contains the material having an acceptor property at a first concentration. The second region contains the material having an acceptor property at a second concentration. Note that the second concentration is higher than zero and lower than the first concentration.

A light emitting diode of an embodiment of the present disclosure includes a first electrode, a hole transport region on an upper portion of the first electrode and having a first refractive index, an emission layer on an upper portion of the hole transport region and having a second refractive index less than the first refractive index, an electron transport region on an upper portion of the emission layer, and a second electrode on an upper portion of the electron transport region.