A condensed cyclic compound represented by Formula 1:

##STR00001## wherein in Formula 1, Ar and R.sub.1 to R.sub.8 are the same as described in the specification.

An electroluminescent device and a display device including the same. The electroluminescent device includes a first electrode and a second electrode facing each other; a light emitting layer disposed between the first electrode and the second electrode, the light emitting layer including a quantum dot; a hole transport layer disposed between the light emitting layer and the first electrode; and an electron transport layer disposed between the light emitting layer and the second electrode, wherein the hole transport layer, the light emitting layer, or a combination thereof includes thermally activated delayed fluorescence material, and the thermally activated delayed fluorescence material is present in an amount of greater than or equal to about 0.01 wt % and less than about 10 weight percent (wt %), based on 100 wt % of the hole transport layer, the light emitting layer, or the combination thereof including the thermally activated delayed fluorescence material.

Objects of the present invention are to provide: a light-emitting element having a long lifetime and good emission efficiency and drive voltage. One embodiment of the invention is a light-emitting element including, between an anode and a cathode, at least a stack structure in which a first layer, a second layer, and a light-emitting layer are provided in order from the anode side. The first layer includes a first organic compound and an electron-accepting compound. The second layer includes a second organic compound having a HOMO level differing from the HOMO level of the first organic compound by from −0.2 eV to +0.2 eV. The light-emitting layer includes a third organic compound having a HOMO level differing from the HOMO level of the second organic compound by from −0.2 eV to +0.2 eV and a light-emitting substance having a hole-trapping property with respect to the third organic compound.

The present disclosure provides an organic light emitting device, including a first electrode, a second electrode and an emitting layer disposed between the first electrode and the second electrode. A hole transporting layer is disposed between the first electrode and the emitting layer. An electron transporting layer is disposed between the second electrode and the emitting layer. The ratio of the hole mobility of the hole transporting layer to the electron mobility of the electron transporting layer is about 10 to 500.

An organometallic compound, represented by Formula 1:

M.sub.1(Ln.sub.1).sub.n1(Ln.sub.2).sub.n2  Formula 1

wherein, Ln.sub.1 is a ligand represented by Formula 1-1, Ln.sub.2 is a ligand represented by Formula 2-1 or Formula 2-2, n1 may be 1 or 2, and n2 may be 1 or 2, wherein the other substituents may be understood by referring to the descriptions thereof provided herein:

##STR00001##

An organometallic compound, represented by Formula 1:

M.sub.1(L.sub.1).sub.n1(Ln.sub.2).sub.n2  Formula 1

wherein M.sub.1 is a transition metal, Ln.sub.1 is a ligand represented by Formula 1-1, Ln.sub.2 is a ligand represented by Formula 2-1 or Formula 2-2, n1 is 1 or 2, and n2 is 1 or 2:

##STR00001##

wherein CY.sub.11, CY.sub.12, X.sub.31, X.sub.32, R.sub.10A, R.sub.10B, R.sub.21 to R.sub.28, R.sub.31 to R.sub.37, R.sub.41 to R.sub.44, b11, and b12 are as defined herein, and * and *′ each indicate a binding site to M.sub.1.

An organic EL device includes: an anode; a cathode; an anode side emitting unit; a cathode side emitting unit; a charge generating unit; a first organic layer having a thickness of 40 nm or less; and a second organic layer, in which the anode side emitting unit includes a first emitting layer which is provided close to the anode, a difference between an ionization potential Ip(H1) of a first host material in the first emitting layer and an ionization potential Ip(EBL) of a first organic material in the first organic layer satisfies a relationship of a numerical formula (Numerical Formula A1) below,

Ip(H1)−Ip(EBL)≤0.4 eV  (Numerical Formula A1).

A light-emitting element includes: a first electrode serving as an anode; a second electrode serving as a cathode; a light-emitting layer, of a first wavelength range, provided between the first electrode and the second electrode; an oxide layer provided between the light-emitting layer of the first wavelength range and the first electrode of the first electrode and the second electrode; and an oxide layer provided between the oxide layer and the second electrode, and having contact with the oxide layer. Either the oxide layer or the oxide layer whichever farther away from the light-emitting layer of the first wavelength range is made of a semiconductor. A density of oxygen atoms in the oxide layer is lower than a density of oxygen atoms in the oxide layer.

A light-emitting element has the following: a cathode; an anode; a light-emitting layer disposed between the cathode and the anode, and containing quantum dots; and a hole transport layer disposed between the anode and light-emitting layer. The hole transport layer has a first region adjacent to the anode. The hole transport layer also has a second region closer to the light-emitting layer than the first region is. The second region adjoins to the light-emitting layer. The first region has an ionization potential larger than an ionization potential of the second region and larger than an ionization potential of the light-emitting layer.

A light emitting element includes a first electrode, a second electrode disposed on the first electrode, and an emission part disposed between the first electrode and the second electrode and including a first emission layer and a second emission layer disposed on the first emission layer, the first emission layer may include a first host, and a first dopant, and the second emission layer may include a hole transport host different from the first host, an electron transport host, and a second dopant. A first hole mobility of the first host may be in a range of about 5.0×10.sup.−6 cm.sup.2/Vs to about 1.0×10.sup.−3 cm.sup.2/Vs, a second hole mobility of a host mixture including the hole transport host and the electron transport host may be in a range of about 1.0×10.sup.−6 cm.sup.2/Vs to about 1.0×10.sup.−4 cm.sup.2/Vs, and the first hole mobility may be larger than the second hole mobility.