Provided are an organic EL device which is practically satisfactory in terms of a light-emitting characteristic, a driving voltage, and durability, and a compound for organic EL devices to be used in the device. The organic EL device is an organic EL device produced by laminating, on a substrate, an anode, a plurality of organic layers including a light-emitting layer, and a cathode, the organic EL device containing, in at least one organic layer selected from the light-emitting layer, a hole-transporting layer, an electron-transporting layer, a hole-blocking layer, and an electron-blocking layer, a boron compound having two indolocarbazolyl groups in a molecule thereof. The boron compound is represented by Y-L-B(A)a-L-Y or Y-L(Z)b-Y, where Y represents an indolocarbazolyl group, L represents an aromatic group, and Z represents a boron-containing group.

The present disclosure provides a nitrogen-containing heterocyclic compound having general formula (I) and an organic photoelectric apparatus thereof.

##STR00001##

where A.sub.1, A.sub.2, A.sub.3, A.sub.4, A.sub.5, A.sub.6, A.sub.7, and A.sub.8 are independently selected from a hydrogen atom, at least one compound having the general formula (II) and at least one compound having the general formula (III),

##STR00002##

where Y.sub.1, Y.sub.2, and Y.sub.3 are independently selected from C and N; R.sub.3 and R.sub.4 are independently selected from C.sub.6-30 aromatic group and C.sub.2-30 heterocyclic aromatic group,

##STR00003##

wherein X is selected from any one of oxyl group (O), sulfhydryl group (S), substituted or non-substituted imino group, substituted or non-substituted methylene group, and substituted or non-substituted silicylene group; R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, R.sub.11, and R.sub.12 are independently selected from hydrogen, deuterium, C.sub.1-30 alkyl group, C.sub.6-30 aromatic group, or C.sub.2-30 heterocyclic aromatic group.

The present disclosure provides a nitrogen-containing heterocyclic compound having a general formula (I) and an organic photoelectric apparatus thereof. The general formula (I) is

##STR00001## wherein A.sub.1, A.sub.2, A.sub.3, A.sub.4, A.sub.5, A.sub.6, A.sub.7, A.sub.8, A.sub.9, and A.sub.10 are independently selected from a hydrogen atom, at least one compound having the general formula (II) and at least one compound having a general formula (III),

##STR00002## wherein Y.sub.1, Y.sub.2, and Y.sub.3 are independently selected from C and N; and R.sub.3 and R.sub.4 are independently selected from C.sub.6-30 aromatic group and C.sub.2-30 heterocyclic aromatic group,

##STR00003## wherein X is selected from oxyl group, sulfenyl group, substituted or non-substituted imino group, substituted or non-substituted methylene group, and substituted or non-substituted silicylene group, and R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, R.sub.11, and R.sub.12 are independently selected from hydrogen, deuterium, C.sub.1-30 alkyl group, C.sub.6-30 aromatic group, and C.sub.2-30 heterocyclic aromatic group.

A dual host system for OLEDs that contains hole-transporting indolocarbazole and electron-transporting indolocarbazole exhibiting superior performance in the OLEDs is disclosed.

Embodiments provide an organometallic compound, a light-emitting device including the organometallic compound, an electronic apparatus including the light-emitting device, and electronic equipment including the light-emitting device. The light-emitting device includes a first electrode, a second electrode facing the first electrode, an interlayer between the first electrode and the second electrode, and the organometallic compound. The organometallic compound is represented by Formula 1, which is explained in the specification:

##STR00001##