The present invention relates to organic light emitting elements, comprising thermally activated delayed fluorescence (TADF) emitters and/or hosts of formula ##STR00001##
which have a sufficiently small energy gap between S.sub.1 and T.sub.1 (ΔE.sub.ST) to enable up-conversion of the triplet exciton from T.sub.1 to S.sub.1. The organic light emitting elements show high electroluminescent efficiency.

An organic electroluminescent device and a display apparatus. The organic electroluminescent device includes a first electrode, a second electrode and an organic layer disposed between the first electrode and the second electrode, where the organic layer includes an emission layer (EML), the EML includes a host material, a thermally activated delayed fluorescence (TADF) sensitizer and a fluorescent dye, and the fluorescent dye is selected from a compound represented by Formula (1).

The present invention relates to the field of display technologies, and particularly to a fused polycyclic compound, a preparation method and use thereof. The fused polycyclic compound provided in the present invention has a structure of General Formula IV. The structure of the compound has ambipolarity, and the HOMO level and the LUMO level of the host material are respectively located on different electron donating group and electron withdrawing group, such that the transport of charges and holes in the host material becomes more balanced, thereby expanding the area where holes and electrons are recombined in the light emitting layer, reducing the exciton concentration, preventing the triplet-triplet annihilation of the device, and improving the efficiency of the device.

Provided is a light-emitting element including a fluorescence-emitting material with high emission efficiency. The light-emitting element includes a pair of electrodes and an EL layer between the pair of electrodes. The EL layer includes a first organic compound, a second organic compound, and a guest material. The first organic compound has a function of emitting a thermally activated delayed fluorescence at room temperature. The guest material has a function of emitting fluorescence. A HOMO level of the first organic compound higher than or equal to a HOMO level of the second organic compound. A LUMO level of the first organic compound is lower than or equal to a LUMO level of the second organic compound.

Provided is a new composition of matter for boron containing organic molecules which can be used as hosts or emitters in OLED devices. The compound can have a structure of Formula I

##STR00001##

The present invention provides a luminescent film containing at least a phosphorescent compound and a fluorescent compound, wherein the convolution integral value J of the emission spectrum of the phosphorescent compound and the absorption spectrum of the fluorescent compound satisfies equation (1), the light emission from the fluorescent compound accounts for at least 90% of the emission spectrum of the luminescent film, and the absolute photoluminescence quantum efficiency (PLQE) of the luminescent film is represented by equation (2). Equation (1): J≥1.5×10.sup.14, Equation (2): PLQE (a film composed of a phosphorescent compound and a host compound)×0.9≤PLQE (a film containing a phosphorescent compound and a fluorescent compound) [The lowest triplet excited state of the host compound is higher than the lowest triplet excited state of the phosphorescent compound, and does not suppress the luminescent property of the phosphorescent compound.]

A compound of Formula I: ##STR00001##
wherein: X.sup.1-X.sup.8 are each independently C or N, wherein two adjacent X.sup.1-X.sup.8 are carbon-fused to a structure of Formula II: ##STR00002## X.sup.9-X.sup.12 are each independently C or N; A.sup.1, A.sup.2, and A.sup.3 are each independently selected from the group consisting of O, S, Se, N, NR, CR, CRR′, SiR, SiRR′, GeR, and GeRR′, with at least one of A.sup.1 and A.sup.2 being N or NR; each occurrence of is independently a single bond or a double bond, wherein one occurrence of is a single bond and one occurrence of is a double bond; each of R.sup.A, R.sup.B, and R.sup.c independently represents zero, mono, or up to a maximum allowed substitution to its associated ring; each of occurrence R, R′, R.sup.A, R.sup.B, and R.sup.C is independently a hydrogen or a substituent selected from the group consisting of Formula III, Formula IV, Formula V, Formula VI, Formula VII, Formula VIII, Formula IX, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, with at least one of R, R′, R.sup.A, R.sup.B, and R.sup.C comprising a group of Formula III, Formula IV, Formula V, Formula VI, Formula VII, Formula VIII, or Formula IX: ##STR00003## ##STR00004## each occurrence of Y.sup.1, Y.sup.2, and Y.sup.3 is independently absent, O, S, Se, NR, CRR′, SiRR′, or GeRR′; each occurrence of Ar.sup.1, and Ar.sup.2 is independently an optionally substituted aryl group or an optionally substituted heteroaryl group, wherein Ar.sup.1 and Ar.sup.2 are optionally joined or fused together to form a ring; each occurrence of X.sup.13-X.sup.20 is independently C or N, with the proviso that at least one of X.sup.13-X.sup.20 is N; each occurrence of A.sup.4 is selected from the group consisting of O, S, Se, NR, CRR′, SiRR′, and GeRR′; each occurrence of R.sup.X independently represents zero, mono, or up to a maximum allowed substitution to its associated ring; each occurrence of R.sup.X is in

The present disclosure relates to an organic compound. The structure of the organic compound consists of a structure represented by formula (I) and a structure represented by formula (II); the structure represented by formula (I) is fused with the structure represented by formula (II); and * represents a connection point, in formula (I), capable of being fused with formula (II). When being used to the organic light-emitting layer of an organic electroluminescent device, the organic compound of the present application can effectively improve the device efficiency of the device and prolong the service life of the organic electroluminescent device.

##STR00001##

Disclosed is a device that includes an emissive material or region including a host that is doped with a first material as an emitter that is an acceptor and a phosphorescent-capable second material as a sensitizer. The first material and the second material each has a first singlet state and a first triplet state. The first triplet state of the second material is not lower than the first triplet state of the first material. The second material transfers excitons to the first material and the excitons that transition to the first triplet state of the first material can be activated to the first singlet state of the first material through a thermal activation process.

Provided are a polycyclic compound represented by Formula 1, an organic light-emitting device including the polycyclic compound, and an electronic apparatus including the organic light-emitting device:

##STR00001##

Formula 1 may be understood by referring to the description of Formula 1 provided herein.