Embodiments provide an organometallic compound, a light-emitting device including the organometallic compound, and an electronic apparatus 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 including an emission layer, and the organometallic compound, which is represented by Formula 1.

##STR00001##

The description of Formula 1 is provided in the specification.

A light-emitting device includes an electron transport region including a first electron transport layer and a second electron transport layer. The first electron transport layer includes a first compound, the second electron transport layer includes a second compound, the first compound includes a pyrimidine group, the second compound includes a triazine group, and an absolute value of a lowest unoccupied molecular orbital (LUMO) energy of the first compound (E.sub.LUMO_E1) is less than an absolute value of a LUMO energy of the second compound (E.sub.LUMO_E2). An electronic apparatus including the light-emitting device.

The present disclosure relates to a plurality of host materials comprising at least one first host compound represented by the following formula 1 and at least one second host compound represented by the following formula 2, and an organic electroluminescent device comprising the same. By comprising the specific combination of the compound according to the present disclosure as host materials, an organic electroluminescent device having high luminous efficiency and/or long lifespan characteristics can be provided.

Provided is an organic electroluminescent device. The organic electroluminescent device is a blue delayed fluorescent device including an anode, a cathode, an emissive layer disposed between the anode and the cathode and a hole blocking layer disposed between the emissive layer and the cathode, where the hole blocking layer comprises a hole blocking material having a structure of Formula 1, and the emissive layer comprises a first host material, a second host material and a blue delayed fluorescent material having a structure of Formula 3. The blue delayed fluorescent device exhibits excellent overall device performance, such as higher efficiency and longer lifetime. Further provided are a light-emitting device comprising a blue delayed fluorescent unit, a green phosphorescent unit and a red phosphorescent unit and a display assembly comprising the blue delayed fluorescent device and the light-emitting device.

The present disclosure relates to a plurality of host materials comprising a first host material having a compound represented by formula 1, and a second host material having a compound represented by formula 2, and an organic electroluminescent device comprising the same. By comprising a specific combination of compounds of the present disclosure as host materials, it is possible to provide an organic electroluminescent device having long lifetime properties while having an equivalent or improved level of power efficiency compared to conventional organic electroluminescent devices.

Provided are organometallic compounds having a structure of

##STR00001##

Also provided are formulations that include these organometallic compounds. Further provided are OLEDs and related consumer products that utilize these organometallic compounds.

An organic light-emitting device including a first electrode; a second electrode facing the first electrode; an emission layer between the first electrode and the second electrode; a hole transport region between the first electrode and the emission layer; and an electron transport region between the emission layer and the second electrode, wherein: the emission layer includes a first compound, at least one of the hole transport region and the electron transport region includes a second compound, the first compound is represented by Formula 1A or 1B, and the second compound is represented by Formula 2A or 2B: ##STR00001##

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, the organic layer including an emission layer, wherein the organic layer includes a first compound, a second compound, a third compound, and a fourth compound, and the first compound to the fourth compound satisfy Equations 1 to 8:
E.sub.1,LUMO≥E.sub.2,LUMO+0.15 electron volts (eV)  Equation 1
E.sub.1,HOMO≥E.sub.2,HOMO+0.15 eV  Equation 2
E.sub.1,T1≥E.sub.4,T1  Equation 3
E.sub.2,T1≥E.sub.4,T1  Equation 4
E.sub.3,T1≥E.sub.4,T1  Equation 5
E.sub.3,LUMO≥E.sub.2,LUMO+0.1 eV  Equation 6
−5.6 eV≥E.sub.3,HOMO  Equation 7
E.sub.gap1≥E.sub.gap3.  Equation 8

A compound and an organic optoelectronic device, the compound being represented by Chemical Formula 1-3a-I or Chemical Formula 1-4a-I: ##STR00001##

The present invention provides the compound represented by Formula 1, an organic electric element comprising a first electrode, a second electrode, and an organic material layer formed between the first electrode and the second electrode, and electronic device thereof, and by comprising the compound represented by Formula 1 in the organic material layer, the driving voltage of the organic electronic device can be lowered, and the luminous efficiency and life time of the organic electronic device can be improved.