An organic electroluminescence device includes: an anode; an emitting layer; and a cathode, the emitting layer containing a first material, a second material and a third material, the first material being a fluorescent material, the second material being a delayed fluorescent material, the third material having a singlet energy larger than a singlet energy of the second material.

A novel light-emitting element is provided. A light-emitting element with a long lifetime is provided. A light-emitting element with high emission efficiency is provided. In the light-emitting element, an EL layer includes a hole-injection layer, a first hole-transport layer, a second hole-transport layer, a third hole-transport layer, a light-emitting layer, a first electron-transport layer, and a second electron-transport layer in this order; the hole-injection layer includes an organic acceptor; the LUMO level of the host material is higher than that of the first electron-transport layer; the LUMO level of the second electron-transport layer is higher than that of the first electron-transport layer; the host material is a substance including a condensed aromatic ring skeleton; and the first and second electron-transport layers each include a substance having a heteroaromatic ring skeleton.

The present invention provides a photoelectric conversion element having excellent heat resistance. In addition, the present invention provides an optical sensor and an imaging element including the photoelectric conversion element. In addition, the present invention provides a compound applied to the photoelectric conversion element. The photoelectric conversion element according to the embodiment of the present invention including a conductive film, a photoelectric conversion film, and a transparent conductive film, in this order, in which the photoelectric conversion film contains a compound represented by Formula (1) or (2). ##STR00001##

Provided is a compound of Chemical Formula 1: ##STR00001## where A and B each independently is a substituted or unsubstituted aryl group, a substituted or unsubstituted monocyclic or dicyclic heteroaryl group, a substituted or unsubstituted dibenzofuran group, a substituted or unsubstituted benzonaphthofuran group, a substituted or unsubstituted dibenzothiophene group, a substituted or unsubstituted benzonaphthothiophene group, a substituted or unsubstituted phenoxazine group, a substituted or unsubstituted phenothiazine group, a substituted or unsubstituted phenanthroline group, a substituted or unsubstituted benzoquinoline group, a substituted or unsubstituted arylamine group, a substituted or unsubstituted silyl group, or a substituted or unsubstituted phosphine oxide group, or one of the following substituents: ##STR00002## and an organic light emitting device including the same.

An organic light-emitting device including a predetermined host and a thermally activated delayed fluorescence emitter.

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.

Provided are an organic electric element comprising as a phosphorescent host material, a mixture of the compounds of Formula (1) and Formula (2), and an organic electronic device or apparatus thereof for achieving a high luminous efficiency, a low driving voltage, and an improved lifespan.

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.

Compounds of formula (1):

##STR00001##

wherein each symbol is as defined in the description, may provide an organic electroluminescence device having a further improved performance.

Provided are: a compound that further improves the capability of an organic EL device, an organic electroluminescent device having a further improved device capability, and an electronic device including the organic electroluminescent device. Precisely provided are: a compound represented by the following formula (1A) or formula (1B) (wherein the symbols are as defined in the description), an organic electroluminescent device containing the compound, and an electronic device including the organic electroluminescent device.

##STR00001##