The device provided herein is an organic electroluminescent device and includes a substrate; a first electrode on the substrate and with high reflectivity; a translucent or transparent second electrode over the first electrode; and a first, a second and a third organic layer included between the first and the second electrode; where the second organic layer has a thickness >80 nm and is made of a second organic material; the third organic layer is a light-emitting layer including at least one light-emitting material and at least one host material; the first organic layer has a conductivity >1×10.sup.−4 S/m and <1×10.sup.−2 S/m; an energy level difference between HOMO energy level of the second organic material and HOMO energy level of the at least one host material is <0.27 eV; and the first electrode and the second organic layer are in direct contact with the first organic layer.

The device provided herein is an organic electroluminescent device and includes a substrate; a first electrode on the substrate and with high reflectivity; a translucent or transparent second electrode over the first electrode; and a first, a second and a third organic layer included between the first and the second electrode; where the second organic layer has a thickness >80 nm and is made of a second organic material; the third organic layer is a light-emitting layer including at least one light-emitting material and at least one host material; the first organic layer has a conductivity >1×10.sup.−4 S/m and <1×10.sup.−2 S/m; an energy level difference between HOMO energy level of the second organic material and HOMO energy level of the at least one host material is <0.27 eV; and the first electrode and the second organic layer are in direct contact with the first organic layer.

A light emitting diode of an embodiment includes a first electrode, a hole transport region disposed on the first electrode, an emission layer disposed on the hole transport region, an electron transport region disposed on the emission layer, and a second electrode disposed on the electron transport region. The hole transport region includes a first hole transport layer disposed adjacent to the first electrode and having a first refractive index, a second hole transport layer disposed adjacent to the emission layer and having a second refractive index, and a third hole transport layer disposed between the first hole transport layer and the second hole transport layer and having a third refractive index which is greater than each of the first refractive index and the second refractive index, thereby showing high light extraction efficiency and high emission efficiency properties.

A light emitting diode of an embodiment includes a first electrode, a hole transport region disposed on the first electrode, an emission layer disposed on the hole transport region, an electron transport region disposed on the emission layer, and a second electrode disposed on the electron transport region. The hole transport region includes a first hole transport layer disposed adjacent to the first electrode and having a first refractive index, a second hole transport layer disposed adjacent to the emission layer and having a second refractive index, and a third hole transport layer disposed between the first hole transport layer and the second hole transport layer and having a third refractive index which is greater than each of the first refractive index and the second refractive index, thereby showing high light extraction efficiency and high emission efficiency properties.

Provided is an organic light-emitting device including a light-emitting layer comprising a compound of Chemical Formula 1, and a first organic material layer comprising a compound of Chemical Formula 2:

##STR00001## wherein: Cy1 to Cy5 are each independently one selected from the group consisting of a substituted or unsubstituted: aromatic hydrocarbon ring, aliphatic hydrocarbon ring, and an aromatic hetero ring, or a ring in which two or more rings selected from the above group are fused, one or more of Cy1 to Cy5 are a ring of the following Chemical Formula 1-A,

##STR00002##

wherein: Ar1 and Ar2 are the same as or different from each other, and are each independently a phenyl, a biphenyl, a terphenyl, a naphthyl, a phenanthrenyl, or a triphenylenyl, where the naphthyl, phenanthrenyl, and triphenylenyl can be substituted with a phenyl.

Provided is an organic light-emitting device including a light-emitting layer comprising a compound of Chemical Formula 1, and a first organic material layer comprising a compound of Chemical Formula 2:

##STR00001## wherein: Cy1 to Cy5 are each independently one selected from the group consisting of a substituted or unsubstituted: aromatic hydrocarbon ring, aliphatic hydrocarbon ring, and an aromatic hetero ring, or a ring in which two or more rings selected from the above group are fused, one or more of Cy1 to Cy5 are a ring of the following Chemical Formula 1-A,

##STR00002##

wherein: Ar1 and Ar2 are the same as or different from each other, and are each independently a phenyl, a biphenyl, a terphenyl, a naphthyl, a phenanthrenyl, or a triphenylenyl, where the naphthyl, phenanthrenyl, and triphenylenyl can be substituted with a phenyl.

Provided is a compound of Formula I

##STR00001##

in which at least one moiety A, moiety B, moiety C, or moiety D is a 6-membered carbocyclic or heterocyclic ring, and at least one R.sup.A, R.sup.B, R.sup.C, or R.sup.D includes a group having Formula II

##STR00002##

where R.sup.X can be silyl, germyl, boryl, nitrile, F, CF.sub.3, cycloalkyl, heterocycloalkyl, or monocyclic heteroaryl. The compounds are useful as emitters in OLEDs providing improved efficiency.

Provided is a compound of Formula I

##STR00001##

in which at least one moiety A, moiety B, moiety C, or moiety D is a 6-membered carbocyclic or heterocyclic ring, and at least one R.sup.A, R.sup.B, R.sup.C, or R.sup.D includes a group having Formula II

##STR00002##

where R.sup.X can be silyl, germyl, boryl, nitrile, F, CF.sub.3, cycloalkyl, heterocycloalkyl, or monocyclic heteroaryl. The compounds are useful as emitters in OLEDs providing improved efficiency.

There is disclosed a compound having Formula I ##STR00001## In Formula, I: Ar.sup.1 is selected from the group consisting of dibenzofuran, dibenzothiophene, or deuterated analogs thereof; Ar.sup.2 and Ar.sup.3 are the same or different and are hydrocarbon aryl, substituted derivatives thereof, or deuterated analogs thereof, with the proviso that Ar.sup.2 and Ar.sup.3 are not the same as Ar.sup.1; a is 0; and Ar.sup.1, Ar.sup.2, and Ar.sup.3 have no additional amino substituents.

There is disclosed a compound having Formula I ##STR00001## In Formula, I: Ar.sup.1 is selected from the group consisting of dibenzofuran, dibenzothiophene, or deuterated analogs thereof; Ar.sup.2 and Ar.sup.3 are the same or different and are hydrocarbon aryl, substituted derivatives thereof, or deuterated analogs thereof, with the proviso that Ar.sup.2 and Ar.sup.3 are not the same as Ar.sup.1; a is 0; and Ar.sup.1, Ar.sup.2, and Ar.sup.3 have no additional amino substituents.