The invention relates to an organic electroluminescent device comprising a light-emitting layer B comprising a host material H.sup.B, a thermally activated delayed fluorescence (TADF) material E.sup.B, and a depopulation agent S.sup.B.

A series of novel donor-acceptor type TADF luminogens have been designed with the aim of developing stable OLEDs with enhanced operational stability and improved color purity. These materials could be found utilization for full color displays and lighting applications.

Provided are an organic electroluminescent device, a display panel, and a display apparatus. An exciton layer adjacent to a light-emitting layer is added, and the exciton layer serves as an exciton recombination region and achieves the effect of increasing the density of excitons, where the singlet-state energy level of the exciton layer is higher than the singlet-state energy level of a host material in the light-emitting layer, and an emission spectrum of the exciton layer and an absorption spectrum of the host material in the light-emitting layer have an overlapping area. Moreover, the exciton layer allows triplet-state excitons formed in the exciton layer to form singlet-state excitons via a reverse intersystem crossing process.

A organic light-emitting element including a positive electrode, a light-emitting layer, and a negative electrode in this order, wherein the light-emitting layer contains a dopant material, a host material, and an assist material, the dopant material is a compound represented by the following general formula [1], the host material is a hydrocarbon compound, and the assist material has a lower LUMO level than the host material. In the formula [1], R.sub.1 to R.sub.10 denote a hydrogen atom, an alkyl group, or the like. X denotes O or S. m denotes an integer in the range of 1 to 3, and n denotes an integer in the range of 0 to 2, provided that m+n is 3. The partial structure IrL.sub.n is any one of structures represented by the following formulae [2] and [3], wherein R.sub.11 to R.sub.21 denote a hydrogen atom, an alkyl group, or the like.

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The present invention relates to organic electroluminescent devices, the emitting layer thereof containing a blend of a luminescent material having a narrow singlet-triplet gap and a fluorescent emission material having high steric shielding.

A light-emitting device including a heterocyclic compound represented by Formula 1 and a phosphorescent dopant, and an electronic apparatus including the light-emitting device are provided. Formula 1 is the same as described in the present specification. The light-emitting device includes: a first electrode, a second electrode facing the first electrode, an interlayer between the first electrode and the second electrode and including an emission layer, and the heterocyclic compound represented by Formula 1.

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A light-emitting device having a light-emitting layer containing a delayed fluorescence emitter and an n-type compound has an extended lifetime and high performance. A compound having a triazine ring substituted by a spiro aromatic group can be used as the n-type compound.

A polycyclic compound represented by Formula 1:

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wherein, in Formulae 1, ring CY.sub.1, ring CY.sub.2, and ring CY.sub.3 are each independently a C.sub.5-C.sub.30 carbocyclic group or a C.sub.1-C.sub.30 heterocyclic group; X.sub.1 is B, N, P, P(═O), P(═S), Al, Ga, As, C(R.sub.4), Si(R.sub.4), or Ge(R.sub.4); Y.sub.1 and Y.sub.2 are each independently O, S, Se, B(R.sub.5), N(R.sub.5), C(R.sub.5)(R.sub.6), Si(R.sub.5)(R.sub.6), Ge(R.sub.5)(R.sub.6), Ga(R.sub.5), As(R.sub.5) P(R.sub.5), P(═O)(R.sub.5), P(═S)(R.sub.5), or Al(R.sub.5); and R.sub.1, R.sub.2, R.sub.3, b1, b2, and b3 are as provided herein.

A composition comprising a first compound, a second compound, and a third compound, wherein the first compound, the second compound, and the third compound are different from each other, the first compound satisfies one of Condition 1 and Condition 2 as described herein, and the second compound includes a compound represented by Formula 1:

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wherein ring A.sub.1 is a condensed cyclic group in which 3 or more cyclic groups are condensed with each other, and the 3 or more cyclic groups are each a C.sub.5-C.sub.30 carbocyclic group or a C.sub.1-C.sub.30 heterocyclic group; a1 is an integer from 1 to 5; b1 is an integer from 3 to 10; and L.sub.1, R.sub.1, and R.sub.2 are as described herein.

A compound is represented by one of formulae (11) to (13). R.sub.1 to R.sub.4 each independently represent a group represented by a formula (1-1) or the like, or a group represented by a formula (2-1), a group represented by a formula (2-2) or the like. At least one of R.sub.1 to R.sub.4 is the group represented by the formula (1-1) or the like. At least one of R.sub.1 to R.sub.4 is the group represented by the formula (2-1), (2-2) or the like. For instance, X.sub.1 represents an oxygen atom, a sulfur atom, or CR.sub.151R.sub.152, R.sub.101 to R.sub.110 and R.sub.151 and R.sub.152 each independently representing a hydrogen atom or a substituent. For instance, R.sub.161 to R.sub.168 and R.sub.171 and R.sub.180 each independently represent a hydrogen atom or a substituent. * each independently represents a bonding position to a carbon atom in a benzene ring in each of formulae (11) to (13): ##STR00001##