The present disclosure relates to a plurality of host materials comprising at least one first host compound and at least one second host compound, and an organic electroluminescent device comprising the same. By comprising a specific combination of compounds according to the present disclosure as host materials, an organic electroluminescent device having a low driving voltage, high luminous efficiency, and long lifespan characteristics can be provided.

An organic light emitting diode (OLED) includes at least one emitting material layer (EML) disposed between two electrodes and including a first compound of a pyrimidine-based organic compound substituted with at least one electron-withdrawing group and a second compound of an organic compound having a tetracene-based core. The OLED can be included in an organic light emitting device. The first compound and the second compound can be the same emitting material layer or adjacently disposed emitting material layers. The OLED can lower its driving voltage and improve its luminous efficiency utilizing the advantages of the first and second compounds by adjusting energy levels between the first and second compounds.

Provided are a heterocyclic compound represented by Formula 1, an organic light-emitting device including the same, and an electronic apparatus including the organic light-emitting device:

##STR00001##

The substituents in Formula 1 are the same as described in the detailed description.

An organic light emitting diode and an organic light emitting device including the same are discussed. The organic light emitting diode can include a first compound represented by a following formula, a second compound as a p-type host, and a third compound as an n-type host in an emitting material layer. As a result, the organic light emitting diode and the organic light emitting device have advantages in the driving voltage, the luminous efficiency and the lifespan.

##STR00001##

A compound comprising a first ligand L.sub.A of Formula I,

##STR00001##

is provided. In Formula I, moiety A is a heterocyclic fused ring system comprising a 5-membered ring fused to a 6-membered ring; moiety B is an aromatic ring or fused ring system; each R.sup.A and R.sup.B is independently a hydrogen or a General Substituent; K is a direct bond, O, or S; at least one of R.sup.A and R.sup.B comprises a substituent R comprising a silyl group or a germyl group; ligand L.sub.A is coordinated to a metal M, which has an atomic mass of at least 40; and metal M may be coordinated to other ligands Formulations, OLEDs, and consumer products containing the same are also provided.

Provided are a light-emitting device including a heterocyclic compound represented by Formula 1 below and an electronic apparatus including the light-emitting device. The detailed description of Formula 1 is the same as described in the present specification.

##STR00001##

A light-emitting that includes a first electrode, a second electrode on the first electrode, and at least one functional layer between the first electrode and the second electrode is provided. At least one functional layer may include an aromatic compound represented by Formula 1. The light-emitting element results in a reduced driving voltage and an improved luminous efficiency.

##STR00001##

An organometallic compound, represented by Formula 1:

M.sub.1(Ln.sub.1).sub.n1(Ln.sub.2).sub.n2  Formula 1

wherein Ln.sub.1 is a ligand represented by Formula 1A, Ln.sub.2 is a ligand represented by Formula 1B, n1 is 1 or 2, and n2 is 1 or 2:

##STR00001##

wherein ring CY.sub.21 is a 5-membered carbocyclic group or a 5-membered heterocyclic group, X.sub.31 and X.sub.32 are each independently O or S, b20 is an integer from 0 to 6, R.sub.11 to R.sub.18, R.sub.20 to R.sub.22, and R.sub.31 to R.sub.37 are as defined herein, and * and *′ each indicates a binding site to M.sub.1.

A heterocyclic compound represented by Formula 1, a light-emitting device including the heterocyclic compound, and an electronic apparatus including the light-emitting device are provided:

##STR00001##

wherein the detailed description of Formula 1 is the same as described in the present specification.

An organometallic compound represented by Formula 1:

M.sub.1(Ln.sub.1).sub.n1(Ln.sub.2).sub.n2  Formula 1

wherein, Ln.sub.1 is a ligand represented by Formula 1A, Ln.sub.2 is a ligand represented by Formula 1B, n1 is 1 or 2, and n2 is 1 or 2,

##STR00001##

wherein ring CY.sub.1 and ring CY.sub.2 are each independently a C.sub.5-C.sub.30 carbocyclic group or a C.sub.1-C.sub.30 heterocyclic group, ring CY.sub.41 is a benzene group, ring CY.sub.42 is a 5-membered aromatic heterocyclic group, X.sub.1 is C or N, X.sub.2 is C or N, Y.sub.1 is O, S, Se, C(R.sub.3)(R.sub.4), N(R.sub.3), or B(R.sub.3), and R.sub.1 to R.sub.4, R.sub.10, R.sub.20, R.sub.31 to R.sub.34, R.sub.40, b10, b20, and b40 are as described herein.