A light-emitting element having low driving voltage and high emission efficiency is provided. In the light-emitting element, a combination of a guest material and a host material forms an exciplex. The guest material is capable of converting triplet excitation energy into light emission. Light emission from the light-emitting layer includes light emission from the guest material and light emission from the exciplex. The percentage of the light emission from the exciplex to the light emission from the light-emitting layer is greater than 0 percent and less than or equal to 60 percent. The energy after subtracting the energy of light emission from the exciplex from the energy of light emission from the guest material is greater than 0 eV and less than or equal to 0.23 eV.

An organic electroluminescence device material comprising a metal complex having a neopentyl group, for example, as shown below; and an organic electroluminescence device comprising a substrate having thereon a pair of electrodes and at least one organic layer between the electrodes, the organic layer containing a light emitting layer, wherein any one of the organic layer contains the organic electroluminescence device material.

##STR00001##

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.

Provided are a near-infrared light-emitting diode including an osmium (Os)-containing organometallic compound and a device including the near-infrared light-emitting diode. The near-infrared light-emitting diode includes: a first electrode; a second electrode; and an organic layer between the first electrode and the second electrode, where the organic layer includes a near-infrared light-emitting layer, the near-infrared light-emitting layer includes the osmium (Os)-containing organometallic compound.

An organometallic compound represented by Formula 1:

M(L.sub.1).sub.n1(L.sub.2).sub.n2Formula 1

wherein, in Formula 1, M is a transition metal, L.sub.1 is a ligand represented by Formula 2A, L.sub.2 is a ligand represented by Formula 2B, n1 is 1 or 2, wherein, when n1 is 2, two groups L.sub.1 are identical to or different from each other, n2 is 1 or 2, wherein, when n2 is 2, two group L.sub.2 are identical to or different from each other, the sum of n1 and n2 is 2 or 3, and L.sub.1 and L.sub.2 are different from each other

##STR00001##

wherein X.sub.1, ring CY.sub.1, ring CY.sub.2, ring CY.sub.14, R.sub.1 to R.sub.3, R.sub.11 to R.sub.14, Z.sub.1 to Z.sub.3, a1, a2, a3, b1, and c1 are the same as described in the description, and * and * in Formulae 2A and 2B each indicate a binding site to M in Formula 1.

A method of making an osmium(II) complex having Formula I, L.sup.1-Os-L.sup.2, wherein L.sup.1 and L.sup.2 are independently a biscarbene tridentate ligand, wherein L.sup.1 and L.sup.2 can be same or different is disclosed. The method includes (a) reacting a precursor of ligand L.sup.1 with an osmium precursor to form an intermediate product, wherein the osmium precursor having the formula OsH.sub.x(PR.sub.3).sub.y, wherein x is an integer from 2 to 6 and y is an integer from 2 to 5, and R is selected from the group consisting of aryl, alkyl and cycloalkyl; and (b) reacting a precursor of ligand L.sup.2 with said intermediate product.

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.

A light-emitting element having low driving voltage and high emission efficiency is provided. In the light-emitting element, a combination of a guest material and a host material forms an exciplex. The guest material is capable of converting triplet excitation energy into light emission. Light emission from the light-emitting layer includes light emission from the guest material and light emission from the exciplex. The percentage of the light emission from the exciplex to the light emission from the light-emitting layer is greater than 0 percent and less than or equal to 60 percent. The energy after subtracting the energy of light emission from the exciplex from the energy of light emission from the guest material is greater than 0 eV and less than or equal to 0.23 eV.

Organic light emitting devices are described wherein the emissive layer comprises a host material containing an emissive molecule, which molecule is adapted to luminesce when a voltage is applied across the heterostructure, and the emissive molecule is selected from the group of phosphorescent organometallic complexes, including cyclometallated platinum, iridium and osmium complexes. The organic light emitting devices optionally contain an exciton blocking layer. Furthermore, improved electroluminescent efficiency in organic light emitting devices is obtained with an emitter layer comprising organometallic complexes of transition metals of formula L.sub.2MX, wherein L and X are distinct bidentate ligands. Compounds of this formula can be synthesized more facilely than in previous approaches and synthetic options allow insertion of fluorescent molecules into a phosphorescent complex, ligands to fine tune the color of emission, and ligands to trap carriers.

Specifically substituted hetero- or carbon-bridged phenylquinazolines of the general formulae (Ia) and (Ib) and a process for their preparation, an electronic device comprising at least one of these compounds, an emitting layer, preferably present in an electronic device, comprising at least one compound of general formulae (Ia) and (Ib) and the use of compounds according to general formulae (Ia) and (Ib) in an electronic device as a host material, a charge transporting material, charge and/or exciton blocking material, preferably as a host material or an electron transporting material.