A compound may have formula (1):

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D.sub.11 and D.sub.12 independently being a group of formula (11), (12), or (13):

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At least one D.sub.11 may be a group of formula (12) or (13). R may be, for instance, a hydrogen atom or an aryl group.

Provided are compounds of Formula I wherein at least one of R.sup.A, R.sup.B, R.sup.C, and R.sup.D represents a group of Formula A. Also provided are formulations comprising these compounds. Further provided are OLEDs and related consumer products that utilize these compounds.

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Provided are compounds comprising at least one ligand L.sub.A, represented by Formula I wherein at least one of R.sup.A and R.sup.B comprises a substituent capable of thermally activated delayed fluorescence, a -deficient heterocycle, or a trisubstituted boron atom. Also provided are formulations comprising these compounds. Further provided are OLEDs and related consumer products that utilize these compounds.

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Provided is a composition A that includes: a first dopant; and a first host; where the first dopant has a HOMO energy HOMODopant and a LUMO energy LUMODopant; the first host has a HOMO energy HOMOHost and a LUMO energy LUMOHost; |LUMOHostHOMODopant|=X1; |LUMODopantHOMOHost|=X2; the first dopant has an optical bandgap energy, Y; at least one of X1 and X2 is less than or equal to Y+0.026 eV; the composition A has a vertical dipole ratio VDR(A); composition B is a reference composition comprising the first dopant and a second host, wherein the second host is

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the composition B having a vertical dipole ratio VDR(B); the ratio of the first dopant and the first host in the composition A is identical to the ratio of the first dopant and second host in the composition B; and VDR(A)VDR(B) is 0.05.

A multicolor light-emitting element using fluorescence and phosphorescence, which has a small number of manufacturing steps owing to a relatively small number of layers to be formed and is advantageous for practical application can be provided. In addition, a multicolor light-emitting element using fluorescence and phosphorescence, which has favorable emission efficiency is provided. A light-emitting element which includes a light-emitting layer having a stacked-layer structure of a first light-emitting layer exhibiting light emission from a first exciplex and a second light-emitting layer exhibiting phosphorescence is provided.

A light emitting element includes a first electrode, a second electrode on the first electrode, and an emission layer between the first electrode and the second electrode and including a first compound represented by Formula 1.

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A compound represented by a formula (1).

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In the formula (1): X.sup.1 to X.sup.4 are each independently a nitrogen atom or CRx; at least one of X.sup.1 to X.sup.4 is a nitrogen atom; a ring A, a ring B, and a ring C are each independently an aromatic hydrocarbon ring or a heterocycle; Ar.sup.1 is a hydrogen atom, an aryl group, or a group represented by a formula (2); and Ar.sup.2 is an aryl group or a group represented by a formula (3).

A multicolor light-emitting element using fluorescence and phosphorescence, which has a small number of manufacturing steps owing to a relatively small number of layers to be formed and is advantageous for practical application can be provided. In addition, a multicolor light-emitting element using fluorescence and phosphorescence, which has favorable emission efficiency is provided. A light-emitting element which includes a light-emitting layer having a stacked-layer structure of a first light-emitting layer exhibiting light emission from a first exciplex and a second light-emitting layer exhibiting phosphorescence is provided.

A light-emitting element which uses a plurality of kinds of light-emitting dopants emitting light in a balanced manner and has high emission efficiency is provided. Further, a light-emitting device, a display device, an electronic device, and a lighting device each having reduced power consumption by using the above light-emitting element are provided. A light-emitting element which includes a plurality of light-emitting layers including different phosphorescent materials is provided. In the light-emitting element, the light-emitting layer which includes a light-emitting material emitting light with a long wavelength includes two kinds of carrier-transport compounds having properties of transporting carriers with different polarities. Further, in the light-emitting element, the triplet excitation energy of a host material included in the light-emitting layer emitting light with a short wavelength is higher than the triplet excitation energy of at least one of the carrier-transport compounds.

A composition including a donor compound and an acceptor compound, wherein the donor compound and the acceptor compound form an exciplex having characteristics described in the specification.