Abstract: A green phosphorescent light-emitting device with a long lifetime is provided. The light-emitting device includes a first electrode, a second electrode, and a light-emitting layer. The light-emitting layer is between the first electrode and the second electrode. The light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent light-emitting substance. The first organic compound includes a heteroaromatic ring skeleton and an aromatic hydrocarbon group. The second organic compound includes a bicarbazole skeleton. The lowest triplet excited level of the first organic compound is derived from only the aromatic hydrocarbon group. The energy of the lowest triplet excited level of the second organic compound is higher than or equal to 2.20 eV and lower than or equal to 2.65 eV.

Abstract: A light-emitting device includes a light-emitting layer containing a light-emitting substance and a first organic compound. The light-emitting substance is an organometallic complex containing a central metal and ligands. One of the ligands includes a skeleton formed by a ring A1 and a pyridine ring bonded to each other. The ring A1 represents an aromatic ring or a heteroaromatic ring. The pyridine ring includes an alkyl group having 1 to 6 carbon atoms and being substituted with deuterium. The first organic compound includes an electron-transport skeleton and first and second substituents that are bonded to the electron-transport skeleton. The electron-transport skeleton includes a heteroaromatic ring having two or more nitrogen atoms. The first substituent includes one or both of an aromatic ring and a heteroaromatic ring. The second substituent includes a skeleton having a hole-transport property.

Abstract: An organic semiconductor device that can achieve high resolution and favorable reliability is provided. The organic semiconductor device is one of a plurality of light-emitting devices formed over an insulating layer, which includes a first electrode, a second electrode, and an organic compound layer. The organic compound layer is positioned between the first electrode and the second electrode. The organic compound layer includes a layer containing a first compound. When differential scanning calorimetry is performed on the first compound in such a manner that a cooling step is performed from the state in which the first compound is melted in a first heating step and a second heating step is successively performed, an exothermic peak is not observed in the cooling step and an exothermic peak and a melting point peak are not observed in the second heating step.

Abstract: An optically active compound having the formula: ##STR1## wherein each of Z and Z' is a single bond, --COO--, --OCO--, --CH.sub.2 CH.sub.2 --, --OCH.sub.2 -- or --CH.sub.2 O--, R is an alkyl group having from 1 to 12 carbon atoms, an alkoxyl group having from 1 to 12 carbon atoms, a cyano group or a halogen atom, each of rings A and B is a 1,4-di-substituted phenylene group or a trans-1,4-di-substituted cyclohexylene group, n is 0 or 1, X is ##STR2## wherein * indicates an optical center, and R' is an alkyl group having from 2 to 12 carbon atoms or ##STR3## where R" is a hydrogen atom, an alkyl or alkoxy group having from 1 to 12 carbon atoms, provided that when X is ##STR4## R is the alkyl group or the alkoxy group.