Provided are an organic-light-emitting device and a display apparatus including the same. The 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 and including at least one light-emitting unit, wherein the at least one light-emitting unit includes: an emission layer; and a hole transport region between the first electrode and the emission layer and including a first hole transport (HT) layer, the emission layer includes a host, the first HT layer includes a first compound, a minimum bond dissociation energy (BDE.sub.1HT) of the first compound is larger than a triplet energy (T.sub.1,host) of the host, and a minimum bond dissociation energy (BDE.sub.host) of the host is larger than the triplet energy (T.sub.1,host) of the host.

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. The emission layer includes at least one organometallic compound of Formula 1, and at least one selected from a second compound and a third compound, where the organometallic compound, the second compound, and the third compound are different from each other. When the emission layer comprises both the second compound and the third compound, the second compound and the third compound form an exciplex, and the organometallic compound and the second compound and/or the third compound do not form an exciplex:
M(L.sub.1).sub.n1(L.sub.2).sub.n2,  Formula 1
wherein in Formula 1, L.sub.1 is represented by Formula 2-1: ##STR00001##

Provided are compounds, formulations comprising compounds, and devices that utilize compounds, where the devices include a substrate, a first electrode, an organic emissive layer comprising an organic emissive material disposed over the first electrode. The device includes an enhancement layer, comprising a plasmonic material exhibiting surface plasmon resonance that non-radiatively couples to the organic emissive material and transfers excited state energy from the organic emissive material to the non-radiative mode of surface plasmon polaritons. The enhancement layer is provided no more than a threshold distance away from the organic emissive layer, where the organic emissive material has a total non-radiative decay rate constant and a total radiative decay rate constant due to the presence of the enhancement layer. At least one of the organic emissive material and the organic emissive layer has a vertical dipole ratio (VDR) value of equal or greater than 0.33.

The present disclosure provides a light emitting diode, a method of preparing the same, and a display device. The light emitting diode includes an anode, a quantum dot light emitting layer, an electron transport layer, a cathode, and a transition layer located between the electron transport layer and the cathode, the cathode including a transparent conductive oxide material, and a material of the transition layer having a work function W.sub.F between an LUMO of a material of the electron transport layer and a work function W.sub.F of a material of the cathode.

Provided is an organic light-emitting device including: an anode; a cathode provided to face the anode; a light-emitting layer provided between the anode and the cathode; a first organic material layer provided between the anode and the light-emitting layer; and a second organic material layer provided between the cathode and the light emitting layer in which each organic material, from among organic materials included in the light-emitting layer and the organic material layers, the band gap energy (E.sub.bg) of each of the organic materials except for a dopant compound is 3 eV or more, the first organic material layer comprises one or more compounds each composed of centrally sp3 carbon, the second organic material layer includes one or more compounds each composed of centrally sp3 carbon, and the first organic material layer and the second organic material layer include three or more compounds each composed of centrally sp3 carbon.

Devices having multiple multicomponent emissive layers are provided, where each multicomponent EML includes at least three components. Each of the components in each EML is a host material or an emitter. The devices have improved color stability and relatively high luminance.

An organometallic compound, represented by Formula 1:

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

wherein, in Formula 1, 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 2-2, n1 is 1 or 2, and n2 is 1 or 2:

##STR00001## wherein, in Formulae 1-1, 2-1, and 2-2, CY.sub.1, X.sub.21 to X.sub.28, X.sub.31, X.sub.32, R.sub.10, R.sub.31 to R.sub.37, R.sub.41 to R.sub.44, and b10 are as defined herein, and * and *′ each indicates a binding site to M.sub.1.

A photoelectric conversion element includes a base, a first electrode on or above the base, an electron-transporting layer on or above the first electrode, a photoelectric conversion layer on or above the electron-transporting layer, a hole-transporting layer on or above the photoelectric conversion layer, and a second electrode on or above the hole-transporting layer. The photoelectric conversion element has a penetration portion penetrating the electron-transporting layer and the photoelectric conversion layer. The photoelectric conversion element includes, in the penetration portion, a material of the hole-transporting layer and a material of the second electrode.

A light-emitting element having high emission efficiency which includes a fluorescent material as a light-emitting substance is provided. A light-emitting element includes a pair of electrodes and an EL layer between the pair of electrodes. The EL layer includes a light-emitting layer. The light-emitting layer includes a host material and a guest material. The host material has a difference of more than 0 eV and less than or equal to 0.2 eV between a singlet excitation energy level and a triplet excitation energy level. The guest material is capable of emitting fluorescence. The triplet excitation energy level of the host material is higher than a triplet excitation energy level of the guest material.

An object of the present invention is to provide a photoelectric conversion element that includes a photoelectric conversion film excellent in the vapor deposition suitability, and that exhibits excellent external quantum efficiency to light at all wavelengths in a red wavelength range, a green wavelength range, and a blue wavelength range. Another object of the present invention is to provide an imaging element, an optical sensor, and a compound related to the photoelectric conversion element.

The photoelectric conversion element includes, in the following order, a conductive film, a photoelectric conversion film, and a transparent conductive film, in which the photoelectric conversion film contains a compound represented by Formula (1).

##STR00001##