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.

A novel compound having a benzimidazole based structure is disclosed that is selected from one of the following structures: ##STR00001##
The compound is useful in improving photophysical performance of OLEDs.

In one aspect, provided is a compound of Formula I,

##STR00001##

In Formula I, M is Pt or Pd; L has the structure

##STR00002##

F.sub.1 is

##STR00003##

or a direct bond; rings A, B, C, D, and F are independently monocyclic rings or multicyclic fused ring systems; each of X.sup.1 to X.sup.10 is independently C or N; each of Z.sup.1 to Z.sup.4 is C or N; each of L.sup.1 to L.sup.5 is a direct bond or an organic linker; each of a, b, c, and d is 0 or 1; each K.sup.1 to K.sup.4 is a direct bond, O, or S; each of Z.sup.1 to Z.sup.4 that is connected to O or S is C; and each R.sup.A, R.sup.B, R.sup.C, R.sup.D, R.sup.E, and R.sup.X is independently hydrogen or a substituent.

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.

A ligand for metal complexes are disclosed, in which an imidazole ring is fused to an aromatic ring as a substituent or an imidazole ring is fused to a six-member ring of the original ligand. The features of these elements within the ligand afford a better device performance in general OLED device.

An organic-EL-display device includes a blue-emitting-organic-EL-device and a red-emitting-organic-EL-device as pixels, in which each of the blue-emitting-organic and the red-emitting-organic-EL-device includes a light-reflection layer, transparent electrode, hole transporting zone, emitting layer, electron transporting zone and semitransmissive electrode in this order, the blue-emitting-organic-EL-device has a blue-emitting layer containing a fluorescent-compound FLB, the red-emitting-organic-EL-device has a red-emitting layer containing a delayed fluorescent compound DFR, the hole transporting zone is provided at a constant film-thickness in a shared manner across the blue-emitting and red-emitting organic EL devices, the red-emitting-organic-EL-device has a resonator structure whose order of interference is first-order between the light reflection layer and the semitransmissive electrode, a film-thickness of the red-emitting layer is less than 50 nm, and a sum of film-thicknesses of the transparent electrode and hole transporting zone in the blue-emitting and red-emitting organic EL devices is less than 40 nm.

The present invention relates to the preparation and application of an O∧C∧N∧N tetradentate platinum (II) complex. The complex of the present invention has a structure as shown in Formula (I) below. Compared with a reference device, the organic light-emitting device prepared by the present invention has better performance improvement, and the novel O∧C∧N∧N tetradentate platinum (II) complex has great application value. The tetradentate platinum (II) complex involved in the present invention is based on a carbazole framework, and has a large π-conjugated rigid planar structure, which can greatly reduce non-radiative energy dissipation such as intramolecular rotation and vibration, and is conducive to improving the luminous efficiency and performance of the platinum (II) complex. The O∧C∧N∧N tetradentate platinum (II) complex metal organic material prepared by the present invention has great application values in organic light-emitting diodes, and is used as a phosphorescent doping material to produce a red light OLED device with high luminous efficiency.

##STR00001##

The present invention relates to a metal complex having a structure of chemical formula (I). The metal complex is applied to an organic light-emitting device which emits deep red or near-infrared light, and shows a lower driving voltage and higher luminous efficiency, and has greatly prolonged service life. Therefore, the metal complex has the potential of being applied in the field of organic light-emitting devices. Also provided is an organic light-emitting device, including a cathode, an anode, and an organic layer. The organic layer is one or more of a hole injection layer, a hole transport layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer; and at least one layer in the organic layer contains the compound of structural formula (I).

##STR00001##

A compound having a Pt tetradentate structure of Formula 1, ##STR00001##
is provided. In the structure of Formula 1, rings C and D each independently represent 5- or 6-membered carbocyclic or heterocyclic ring; L.sup.1, L.sup.2, and L.sup.3 are each independently a direct bond, BR, NR, PR, O, S, Se, C═O, S═O, SO.sub.2, SiRR′, GeRR′, alkyl, cycloalkyl, or a combination thereof; the sum of n1 and n2 is 1 or 2; X is selected from NR.sup.E, O, S, and Se; X.sup.3 and X.sup.4 each independently carbon or nitrogen; and one of Q.sup.1, Q.sup.3, and Q.sup.4 is oxygen, and the remaining two of Q.sup.1, Q.sup.3, and Q.sup.4 each represents a direct bond. Formulations and devices, such as an OLEDs, that include the compound of Formula 1 are also described.

An organometallic compound represented by Formula 1A: ##STR00001## wherein, in Formula 1A, groups and variables are the same as described in the specification.