A multicolor light-emitting device having high luminous efficiency is provided. The light-emitting device contains a material serving as an energy donor, a fluorescent material, and a phosphorescent material in a light-emitting layer. The material serving as an energy donor has a function of converting triplet excitation energy into light emission. The molecular structure of the fluorescent material includes a luminophore and protecting groups, and five or more protecting groups are contained in one molecule of a guest material. Introduction of protecting groups into molecules inhibits triplet excitation energy transfer from the material serving as an energy donor to the light-emitting material by the Dexter mechanism. Each of the protecting groups is an alkyl group or a branched-chain alkyl group. In the light-emitting device, light emission is obtained from both the fluorescent material and the phosphorescent material.

Disclosed herein are metal complexes that exhibit multiple radiative decay mechanisms, together with methods for the preparation and use thereof.

An organic electroluminescence device includes a first emitting unit, a first charge generating layer, a second emitting unit, a second charge generating layer, and a third emitting unit provided between an anode and a cathode in this order from the anode, in which the second charge generating layer includes an N layer close to the anode and a P layer close to the cathode, the third emitting layer contains a blue fluorescent compound, at least one of the first or second emitting layer contains a blue fluorescent compound, the third emitting unit includes a hole transporting zone between the second charge generating layer and the third emitting layer, the hole transporting zone is in contact with the second charge generating layer, and a thickness of the hole transporting zone is in a range from 5 nm to 40 nm and smaller than a thickness of the N layer.

An OLED lighting device comprising: a blue light-emitting unit with a blue-light fluorescent, phosphorescent or TADF emitter; a yellow light-emitting electroluminescent unit comprising a green phosphorescent emitter, a red phosphorescent emitter and at least one non-emitting host; wherein the blue light-emitting unit and the yellow light-emitting unit are separated by a mixed interlayer with two non-emitting charge-carrier materials. Desirably, the yellow-light emitting unit essentially consists of a green phosphorescent emitter, a red phosphorescent emitter and a single non-emitting host. The mixed interlayer desirably has more than 50% of a hole-transporting material and an electron-transporting material. The Triplet Energy of both materials in the mixed interlayer can be higher than the Triplet Energies of the R and G phosphorescent dopants. The HOMOs of both materials in the mixed interlayer are more negative than the HOMO of the host in the yellow unit but less negative than the HOMO of the host in the blue unit. The LUMOs of the materials in the mixed interlayer can be more negative than the LUMO of the host in the yellow unit but less negative than the LUMO of the host in the blue unit. The OLED lighting device is spectrally tunable according to the supplied power.

An object of one embodiment of the present invention is to provide a multicolor light-emitting element that utilizes fluorescence and phosphorescence and is advantageous for practical application. The light-emitting element has a stacked-layer structure of a first light-emitting layer containing a host material and a fluorescent substance, a separation layer containing a substance having a hole-transport property and a substance having an electron-transport property, and a second light-emitting layer containing two kinds of organic compounds that form an exciplex and a substance that can convert triplet excitation energy into luminescence. Note that a light-emitting element in which light emitted from the first light-emitting layer has an emission spectrum peak on the shorter wavelength side than an emission spectrum peak of the second light-emitting layer is more effective.

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.

An organic light-emitting device and display apparatus, the device including a first electrode; a second electrode facing the first electrode; an emission layer between the first and second electrode; a hole control layer between the first electrode and the emission layer; and an electron control layer between the emission layer and the second electrode, wherein the emission layer includes a plurality of sub-emission layers to emit light having different wavelengths, at least portions of the plurality of sub-emission layers do not overlap one another, the plurality of sub-emission layers include: a first sub-emission layer including a first color light-emitting dopant, and a second sub-emission layer including a second color light-emitting dopant, the first and second sub-emission layers each include a hole-transporting and electron-transporting host which form an exciplex, and a triplet energy of the exciplex is equal to or greater than triplet energies of the first and second color light-emitting dopant.

Organic compounds containing indolocarbazoles as electron donor connected with electron acceptors such aza-triphenylene or dibenzoquinoxaline that can improve the performance of phosphorescent organic light emitting devices are disclosed.

It is an object of the present invention to provide an image display apparatus capable of inhibiting or preventing the deterioration of a light conversion layer while high luminous efficiency and high color reproducibility are achieved. The present invention provides a light-emitting device including a pair of electrodes, an electroluminescent layer disposed between a first electrode and a second electrode, a light conversion layer including multiple pixels and converting light that is emitted from the electroluminescent layer and that has a blue emission spectrum into light having a different wavelength. The light conversion layer includes pixels of three primary colors of red (R), green (G), and blue (B) and contains a light-emitting nanocrystal having an emission spectrum in any of red (R), green (G), and blue (B) when light from the electroluminescent layer is incident on at least one of the three primary colors.

An object is to provide a light-emitting element with high emission efficiency. The light-emitting element contains first to third organic compounds. The first organic compound has a function of converting triplet excitation energy into light. The second organic compound has a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton. The third organic compound is a fluorescent compound. Light emitted from the light-emitting element is light emitted from the third organic compound that receives excitation energy from the first organic compound or from an exciplex formed by the first and second organic compounds.