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.

A composition which is useful for producing a light emitting device having excellent external quantum efficiency contains two or more compounds represented by the formula (C-1) and a phosphorescent compound, in which at least one of the compounds represented by the formula (C-1) is a compound in which R.sup.C is a group represented by the formula (C′-1). ##STR00001##
Ring R.sup.1C and Ring R.sup.2C represent an aromatic hydrocarbon ring or an aromatic hetero ring. R.sup.C represents an oxygen atom, a sulfur atom or a group represented by the formula (C′-1). ##STR00002##
Ring R.sup.3C and Ring R.sup.4C represent an aromatic hydrocarbon ring or an aromatic hetero ring. R.sup.C′ represents a carbon atom, a silicon atom, a germanium atom, a tin atom or a lead atom.

A composition which is useful for producing a light emitting device having excellent external quantum efficiency contains two or more compounds represented by the formula (C-1) and a phosphorescent compound, in which at least one of the compounds represented by the formula (C-1) is a compound in which R.sup.C is a group represented by the formula (C′-1). ##STR00001##
Ring R.sup.1C and Ring R.sup.2C represent an aromatic hydrocarbon ring or an aromatic hetero ring. R.sup.C represents an oxygen atom, a sulfur atom or a group represented by the formula (C′-1). ##STR00002##
Ring R.sup.3C and Ring R.sup.4C represent an aromatic hydrocarbon ring or an aromatic hetero ring. R.sup.C′ represents a carbon atom, a silicon atom, a germanium atom, a tin atom or a lead atom.

Disclosed herein are new antiviral compounds, together with pharmaceutical compositions that include one or more antiviral compounds, and methods of synthesizing the same. Also disclosed herein are methods of ameliorating and/or treating a paramyxovirus viral infection with one or more small molecule compounds. Examples of paramyxovirus infection include an infection caused by human respiratory syncytial virus (RSV).

Disclosed herein are new antiviral compounds, together with pharmaceutical compositions that include one or more antiviral compounds, and methods of synthesizing the same. Also disclosed herein are methods of ameliorating and/or treating a paramyxovirus viral infection with one or more small molecule compounds. Examples of paramyxovirus infection include an infection caused by human respiratory syncytial virus (RSV).

An organic electroluminescence device having an improved performance and a compound represented by formula (1), which is a novel material that enables the organic electroluminescence device:

##STR00001## wherein, X, Ar.sup.1 to Ar.sup.5, R.sup.1 to R.sup.20, *a, and *b are the same as those defined in the specification.

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.

An organic compound having a tetraphenyl moiety and at least one fused hetero aryl moiety having at least one oxygen and/or sulfur on a ring and bonded to the tetraphenyl moiety directly or indirectly, and a light emitting diode and a light emitting device having the organic compound are disclosed. The organic compound has excellent thermal resistance property and hole mobility property. The organic compound can be incorporated into a hole transfer layer, an electron blocking layer and/or a charge generation layer of the light emitting diode. Therefore, the light emitting diode and light emitting device according to the present invention have decreased driving voltage and enhanced luminous efficiency.

An organic compound having a tetraphenyl moiety and at least one fused hetero aryl moiety having at least one oxygen and/or sulfur on a ring and bonded to the tetraphenyl moiety directly or indirectly, and a light emitting diode and a light emitting device having the organic compound are disclosed. The organic compound has excellent thermal resistance property and hole mobility property. The organic compound can be incorporated into a hole transfer layer, an electron blocking layer and/or a charge generation layer of the light emitting diode. Therefore, the light emitting diode and light emitting device according to the present invention have decreased driving voltage and enhanced luminous efficiency.