Provided are compounds comprising anionic bidentate ligands L.sub.A that are ligands of Pt and Ir complexes for OLED applications. Also provided are formulations comprising these compounds comprising anionic bidentate ligands L.sub.A that are ligands of Pt and Ir complexes for OLED applications. Further provided are OLEDs and related consumer products that utilize these compounds comprising anionic bidentate ligands L.sub.A that are ligands of Pt and Ir complexes for OLED applications.

Provided is a polycyclic compound of Formula 100:

##STR00001## where Cy3 and Cy4 are the same as or different from each other, and are each independently one selected from the group consisting of a substituted or unsubstituted aromatic hydrocarbon ring, a substituted or unsubstituted aliphatic hydrocarbon ring, and a substituted or unsubstituted aromatic hetero ring, or a ring in which two or more rings selected from the group are fused,
and an organic light-emitting element comprising the same.

An organic light emitting device including a light emitting layer, which comprises one or more of compounds represented by Formulae 1-1 to 1-3; and a compound represented by Formula 2.

##STR00001## ##STR00002##

A polycyclic compound represented by Formula 1:

##STR00001##

wherein, in Formulae 1, ring CY.sub.1, ring CY.sub.2, and ring CY.sub.3 are each independently a C.sub.5-C.sub.30 carbocyclic group or a C.sub.1-C.sub.30 heterocyclic group; X.sub.1 is B, N, P, P(═O), P(═S), Al, Ga, As, C(R.sub.4), Si(R.sub.4), or Ge(R.sub.4); Y.sub.1 and Y.sub.2 are each independently O, S, Se, B(R.sub.5), N(R.sub.5), C(R.sub.5)(R.sub.6), Si(R.sub.5)(R.sub.6), Ge(R.sub.5)(R.sub.6), Ga(R.sub.5), As(R.sub.5) P(R.sub.5), P(═O)(R.sub.5), P(═S)(R.sub.5), or Al(R.sub.5); and R.sub.1, R.sub.2, R.sub.3, b1, b2, and b3 are as provided herein.

A composition comprising a first compound, a second compound, and a third compound, wherein the first compound, the second compound, and the third compound are different from each other, the first compound satisfies one of Condition 1 and Condition 2 as described herein, and the second compound includes a compound represented by Formula 1:

##STR00001##

wherein ring A.sub.1 is a condensed cyclic group in which 3 or more cyclic groups are condensed with each other, and the 3 or more cyclic groups are each a C.sub.5-C.sub.30 carbocyclic group or a C.sub.1-C.sub.30 heterocyclic group; a1 is an integer from 1 to 5; b1 is an integer from 3 to 10; and L.sub.1, R.sub.1, and R.sub.2 are as described herein.

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

##STR00001## wherein details of Formula 1 are the same as described in the present specification.

Provided is a light emitting device including a first electrode, a hole transport region on the first electrode, a first light emitting layer on the hole transport region and emitting light of a first wavelength, a second light emitting layer on the hole transport region and emitting light of a second wavelength different from the first wavelength, an electron transport region on the first light emitting layer and the second light emitting layer, and a second electrode on the electron transport region. The second light emitting layer includes a first sub-light emitting layer including a first host having a first hole transporting host and a first electron transporting host and a dopant emitting light of the second wavelength, and a second sub-light emitting layer including a second host and a second hole transporting host, but not including the dopant. The light emitting device provides improved light emitting efficiency.

A semiconductor nanoparticle, a production method thereof, and an electroluminescent device including the same. The production method includes: combining a magnesium precursor and an additive with a chalcogen precursor in a reaction medium including an organic solvent and an organic ligand; heating the reaction medium to a reaction temperature; and reacting the magnesium precursor and the chalcogen precursor in the presence of the additive to form a magnesium chalcogenide, wherein the semiconductor nanoparticle comprises the magnesium chalcogenide, wherein the magnesium chalcogenide comprises magnesium; and selenium, sulfur, or a combination thereof, and wherein the additive includes a hydride compound including an alkali metal, calcium, barium, aluminum, or a combination thereof.

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 and comprising a fluorescent emission layer. The fluorescent emission layer includes a first host (H1), a second host (H2), a first dopant (D1), and a second dopant (D2).

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