An organic light-emitting device which including a first electrode, a second electrode facing the first electrode, and an emission layer disposed between the first electrode and the second electrode, wherein an emission layer includes a first material, a second material, and a third material satisfying certain conditions.

A light-emitting element is provided. The light-emitting element includes first and second electrodes and an EL layer therebetween. The EL layer includes a light-emitting layer containing first and second substances. The amount of the first substance is larger than that of the second substance. The second substance emits light. Average transition dipole moments of the second substance are divided into three components in x-, y-, and z-directions which are orthogonal to each other. Components parallel to the first or second electrode are assumed to be the components in the x- and y-directions, and a component perpendicular to the first or second electrode is assumed to be the component in the z-direction. The proportion of the component in the z-direction is represented by a, which is less than or equal to 0.2.

An organic EL device includes: an anode; a cathode; an emitting region; and a hole transporting zone, in which the emitting region includes a first emitting layer containing a first host material and a second emitting layer containing a second host material, at least one organic layer in the hole transporting zone is a first organic layer, the first organic layer contains a hole transporting zone material, the first emitting layer is disposed close to the anode, and a triplet energy of the first host material T.sub.1(H1) and a triplet energy of the second host material T.sub.1(H2) satisfy Numerical Formula 1, and a dipole of the first host material is 0.4 D or more,

T.sub.1(H1)>T.sub.1(H2)(Numerical Formula 1).

The present disclosure provides an organic light-emitting diode structure and a display device. In the organic light-emitting diode structure, the light-emitting layer, the hole blocking layer and the electron blocking layer satisfy the following conditions: T1 (HBL)>T1 (Host); T1 (EBL)>T1 (Host); T1 (Dopant)>T1 (Host); S1 (Host)>S1 (Dopant); wherein T1 (HBL) is the lowest triplet energy of the hole blocking layer material, T1 (Host) is the lowest triplet energy of the host material, T1 (EBL) is the lowest triplet energy of the electron blocking layer material, T1 (Dopant) is the lowest triplet energy of the guest material, S1 (Host) is the lowest singlet energy of the host material, and S1 (Dopant) is the lowest singlet energy of the guest material.

Arrangements for phosphorescent blue emissive materials, layers, and devices are provided. The arrangements include a host having first a triplet energy level of at least 2.8 eV and an absolute difference of not more than 0.3 eV between the first singlet and triplet energy levels, and an emitter that includes an emissive transition metal complex and a first triplet energy level of at least 2.7 eV.

A light-emitting element with high emission efficiency which includes fluorescent materials is provided. The light-emitting element includes a first light-emitting layer and a second light-emitting layer. The first light-emitting layer includes a first fluorescent material and a first host material, and the second light-emitting layer includes a second fluorescent material and a second host material. The second host material includes a first organic compound and a second organic compound. The first organic compound and the second organic compound form an exciplex. A singlet excited energy level of the first host material is higher than a singlet excited energy level of the first fluorescent material, and a triplet excited energy level of the first host material is lower than a triplet excited energy level of the first fluorescent material.

A light-emitting device and method for using quantum dot LEDs are provided in the present application. The light-emitting device includes at least one quantum dot LED, wherein the quantum dot LED includes a first electrode, an electron transport layer, a quantum dot layer, a hole transport layer, and a second electrode which are sequentially stacked; a fluorescence quantum yield of quantum dots in the quantum dot layer is equal to or greater than 50%; a ratio of an average photon voltage to an operating voltage of the quantum dot LED is equal to or greater than 1; electroluminescence of the quantum dot LED includes thermoelectrically-assisted up-conversion luminescence. The quantum dot LED can achieve higher external power conversion efficiency in the light-emitting device.

A light-emitting element is provided. The light-emitting element includes first and second electrodes and an EL layer therebetween. The EL layer includes a light-emitting layer containing first and second substances. The amount of the first substance is larger than that of the second substance. The second substance emits light. Average transition dipole moments of the second substance are divided into three components in x-, y-, and z-directions which are orthogonal to each other. Components parallel to the first or second electrode are assumed to be the components in the x- and y-directions, and a component perpendicular to the first or second electrode is assumed to be the component in the z-direction. The proportion of the component in the z-direction is represented by a, which is less than or equal to 0.2.

An organic light-emitting device and an electronic apparatus including the same are provided. The organic light-emitting device includes a first electrode, a second electrode facing the first electrode, and an interlayer provided between the first electrode and the second electrode and including an emission layer, wherein the emission layer includes a first compound that is a hole-transporting compound, a second compound that is an electron-transporting compound, a third compound capable of emitting phosphorescence, and a fourth compound capable of emitting delayed fluorescence, and a value of R.sup.0 is at least 3.5 nm.

A light-emitting element with high emission efficiency which includes fluorescent materials is provided. The light-emitting element includes a first light-emitting layer and a second light-emitting layer. The first light-emitting layer includes a first fluorescent material and a first host material, and the second light-emitting layer includes a second fluorescent material and a second host material. The second host material includes a first organic compound and a second organic compound. The first organic compound and the second organic compound form an exciplex. A singlet excited energy level of the first host material is higher than a singlet excited energy level of the first fluorescent material, and a triplet excited energy level of the first host material is lower than a triplet excited energy level of the first fluorescent material.