Disclosed are a light emitting element and a display device including the same, wherein a hole generation layer is further provided between a hole transport layer and an emission layer, in addition to an electron blocking layer, in order to control the speed of electrons and holes introduced into the emission layer, whereby it is possible to prevent accumulation of carriers at the electron blocking layer or the hole transport layer, and therefore it is possible to reduce turn-on voltage, to maintain uniform efficiency irrespective of change in current density, to prevent defects at specific gradation, and to increase lifetime.

A light-emitting device includes an electron transport region including a first electron transport layer and a second electron transport layer. The first electron transport layer includes a first compound, the second electron transport layer includes a second compound, the first compound includes a pyrimidine group, the second compound includes a triazine group, and an absolute value of a lowest unoccupied molecular orbital (LUMO) energy of the first compound (E.sub.LUMO_E1) is less than an absolute value of a LUMO energy of the second compound (E.sub.LUMO_E2). An electronic apparatus including the light-emitting device.

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.

An organic light-emitting device including a first electrode; a second electrode facing the first electrode; an emission layer between the first electrode and the second electrode; a hole transport region between the first electrode and the emission layer; and an electron transport region between the emission layer and the second electrode, wherein: the emission layer includes a first compound, at least one of the hole transport region and the electron transport region includes a second compound, the first compound is represented by Formula 1A or 1B, and the second compound is represented by Formula 2A or 2B: ##STR00001##

An organic light emitting device includes: a first electrode; a second electrode facing the first electrode; and an organic layer between the first electrode and the second electrode, the organic layer including an emission layer, wherein the organic layer includes a first compound, a second compound, a third compound, and a fourth compound, and the first compound to the fourth compound satisfy Equations 1 to 8:
E.sub.1,LUMO≥E.sub.2,LUMO+0.15 electron volts (eV)  Equation 1
E.sub.1,HOMO≥E.sub.2,HOMO+0.15 eV  Equation 2
E.sub.1,T1≥E.sub.4,T1  Equation 3
E.sub.2,T1≥E.sub.4,T1  Equation 4
E.sub.3,T1≥E.sub.4,T1  Equation 5
E.sub.3,LUMO≥E.sub.2,LUMO+0.1 eV  Equation 6
−5.6 eV≥E.sub.3,HOMO  Equation 7
E.sub.gap1≥E.sub.gap3.  Equation 8

An organic light-emitting device including a first electrode, a second electrode, an emission layer disposed between the first electrode and the second electrode, a hole transport region disposed between the first electrode and the emission layer, and an electron transport region disposed between the emission layer and the second electrode, wherein the emission layer includes a host and a dopant, wherein the dopant is an iridium-free organometallic compound, and wherein a dopant concentration profile of the emission layer satisfies predetermined parameters disclosed in the specification.

The present disclosure provides an organic emitting compound of the following Formula, and an organic light emitting diode, which includes a first electrode; a second electrode facing the first electrode; and a first emitting material layer positioned between the first electrode and the second electrode and including a first host and the organic emitting compound, and an organic light emitting display device including the organic light emitting diode. ##STR00001##

An organometallic compound is represented by Formula 1. An organic light-emitting device includes a first electrode, a second electrode, and an organic layer including an emission layer between the first electrode and the second electrode, wherein the organic layer includes at least one of the organometallic compound represented by Formula 1. An apparatus includes the organic light-emitting device.

Provided is a compound including a first ligand L.sub.A of Formula I,

##STR00001##

In Formula I, moiety A is a monocyclic ring or a multicyclic fused ring system; one of X.sup.1, X.sup.2, and X.sup.3 is C and is connected to X.sup.4; one of X.sup.1, X.sup.2, and X.sup.3 is N and is coordinated to a metal M; and the remaining one of X.sup.1, X.sup.2, and X.sup.3 is CR or N; X.sup.4 is C or N; Y is a divalent linking group; each R, R′, R.sup.A, and R.sup.B is independently hydrogen or a General Substituent; each of K.sup.1 and K.sup.2 is independently direct bond, O, or S; and metal M is selected from the group consisting of Os, Ir, Pd, Pt, Cu, Ag, and Au. Formulations, OLEDs, and consumer products including the same are also provided.

An organometallic compound represented by Formula 1:

M.sub.1(L.sub.11).sub.n11(L.sub.12).sub.n12  Formula 1

wherein, in Formula 1, M.sub.1 is a first-row transition metal, a second-row transition metal, or a third-row transition metal, L.sub.11 is a ligand represented by Formula 1-1, L.sub.12 is a monodentate ligand or a bidentate ligand, n11 is 1, and n12 is 0, 1, or 2:

##STR00001##

wherein ring CY.sub.1 to ring CY.sub.4, E.sub.1, T.sub.1 to T.sub.4, R.sub.10 to R.sub.40, X.sub.1 to X.sub.4, n1 to n4, a1 to a4, and c10 to c40 may each be understood by referring to the descriptions thereof provided herein, and *1, *2, *3, and *4 are each a binding site to M.sub.1 in Formula 1.