A compound having the formula [L.sub.A].sub.yIr[L.sub.B].sub.x is disclosed, where L.sub.A is selected from one of the following: ##STR00001##
The compounds have at least one pyridyl dibenzo-substituted ligand that coordinates to metal center from the sterically hindered position as exemplified by L.sub.A. Because of this unique configuration, the compounds display better photo-physical and thermal properties and can be used in OLED devices to improve their performance, particularly with respect to the device's lifetime.

A light-emitting device includes: a first electrode; a second electrode facing the first electrode; and an interlayer disposed between the first electrode and the second electrode and including an emission layer; wherein the interlayer further includes: a layer A including an oxide of an inorganic compound; a layer B adjacent to an upper portion of the layer A and including an oxide of an inorganic compound; and a layer C adjacent to a lower portion of the layer A and including an oxide of an inorganic compound, and relationships between a refractive index a of the layer A, a refractive index b of the layer B, and a refractive index c of the layer C satisfy the Equations (1) and (2) defined herein.

An organic light-emitting device including: a first electrode; a second electrode facing the first electrode; a first emission unit and a second emission unit between the first electrode and the second electrode; and a first charge generation layer between the first emission unit and the second emission unit; wherein the first emission unit includes a first emission layer and a first inorganic buffer layer, and the second emission unit includes a second emission layer and a second inorganic buffer layer.

The present disclosure relates to a plurality of host materials and an organic electroluminescent device comprising the same. The organic electroluminescent device of the present disclosure can exhibit excellent lifespan characteristics while maintaining high luminous efficiency by including a specific combination of a plurality of host compounds.

To provide a light-emitting element which uses a fluorescent material as a light-emitting substance and has higher luminous efficiency. To provide a light-emitting element which includes a mixture of a thermally activated delayed fluorescent substance and a fluorescent material. By making the emission spectrum of the thermally activated delayed fluorescent substance overlap with an absorption band on the longest wavelength side in absorption by the fluorescent material in an S.sub.1 level of the fluorescent material, energy at an S.sub.1 level of the thermally activated delayed fluorescent substance can be transferred to the S.sub.1 of the fluorescent material. Alternatively, it is also possible that the S.sub.1 of the thermally activated delayed fluorescent substance is generated from part of the energy of a T.sub.1 level of the thermally activated delayed fluorescent substance, and is transferred to the S.sub.1 of the fluorescent material.

A new type of charge transport layer based on organometal halide perovskite for highly efficient organic light emitting diodes (OLEDs) is demonstrated. By solution processing of halide perovskite precursors, smooth essentially pure perovskite thin films may be prepared with high transparency and conductivity. Solution processed multilayer OLED with this perovskite-based hole transport layer outperforms a device with a PEDOT:PSS layer.

A compound that is capable of achieving an organic EL device that has a high external quantum efficiency and a long lifetime is to be provided, and a compound represented by the following formula (1) is used (wherein in the formula, R.sub.11 to R.sub.17, R.sub.21 to R.sub.28, R.sub.31 to R.sub.38, R.sub.41 to R.sub.45, R.sub.51 to R.sub.55, R.sub.61 to R.sub.64, and L.sub.1 are defined in the description). ##STR00001##

Disclosed are an organic light emitting device and a display device using the same in which a light emitting layer includes a host and a plurality of dopants. In the light emitting layer, energy is transferred from a host and other dopants to one dopant by energy transfer system, thus it is possible to increase luminous efficacy of a single color and to increase lifetime of emission.

A light-emitting element which includes a plurality of light-emitting layers between a pair of electrodes and has low driving voltage and high emission efficiency is provided. A light-emitting element including first to third light-emitting layers between a cathode and an anode is provided. The first light-emitting layer includes a first phosphorescent material and a first electron-transport material; the second light-emitting layer includes a second phosphorescent material and a second electron-transport material; the third light-emitting layer includes a fluorescent material and a third electron-transport material; the first to third light-emitting elements are provided in contact with an electron-transport layer positioned on a cathode side; and a triplet excitation energy level of a material included in the electron-transport layer is lower than triplet excitation energy levels of the first electron-transport material and the second electron-transport material.

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.