The present invention relates to an organic electroluminescent device including at least one light-emitting layer B composed of one or more sublayers, wherein the one or more sublayers of the light-emitting layer B as a whole include at least one host material H.sup.B, at least one phosphorescence material P.sup.B, at least one small FWHM emitter S.sup.B, and optionally at least one TADF material E.sup.B, wherein S.sup.B emits light with a full width at half maximum (FWHM) of less than or equal to 0.25 eV.

Emission efficiency of a light-emitting element is improved. The light-emitting element has a pair of electrodes and an EL layer between the pair of electrodes. The EL layer includes a first light-emitting layer and a second light-emitting layer. The first light-emitting layer includes a fluorescent material and a host material. The second light-emitting layer includes a phosphorescent material, a first organic compound, and a second organic compound. An emission spectrum of the second light-emitting layer has a peak in a yellow wavelength region. The first organic compound and the second organic compound form an exciplex.

A compound of Chemical Formula 1:

##STR00001##

and an organic light emitting device including the same.

Emission efficiency of a light-emitting element is improved. The light-emitting element has a pair of electrodes and an EL layer between the pair of electrodes. The EL layer includes a first light-emitting layer and a second light-emitting layer. The first light-emitting layer includes a fluorescent material and a host material. The second light-emitting layer includes a phosphorescent material, a first organic compound, and a second organic compound. An emission spectrum of the second light-emitting layer has a peak in a yellow wavelength region. The first organic compound and the second organic compound form an exciplex.

The compound represented by formula (1):

##STR00001##

wherein A, B, R.sup.1, and R.sup.2 are as defined in the description,
provides organic electroluminescence (EL) devices having a high emission efficiency when operated at low voltage and a long lifetime and electronic devices including such organic EL devices.

Disclosed is an organic electroluminescent device, comprising a substrate and light emitting units formed in sequence on the substrate, characterized in that, each of the light emitting units comprises a first electrode layer (1), a light emitting layer (2) and a second electrode layer (3), the light emitting layer comprises a host material and a dye, the host material is made of materials having both electron transport capability and hole transport capability; at least one material in the host material has a CT excited triplet state energy level T.sub.1 greater than its n-π excited triplet state energy level S.sub.1, and T.sub.1-S.sub.1≤0.3 eV; or, at least one material in the host material has a CT excited triplet state energy level T.sub.1 greater than its n-π excited triplet state energy level S.sub.1, and T.sub.1-S.sub.1≥1 eV, with the difference between its n-π excited second triplet state energy level and its CT excited first singlet state energy level being in the range of −0.1 eV to 0.1 eV. The organic electroluminescent device configuration can sufficiently utilize the triplet state energy in the host material and the dye to increase the luminous efficiency and prolong the service life of the device.

An organic electroluminescent device comprises an anode, a first organic light emitting layer, an exciton control layer, a second organic light emitting layer, and a cathode that are successively stacked, wherein the first organic light emitting layer comprises a hole transport type host material and a first doped material; the exciton control layer is provided on the surface of the first organic light emitting layer away from the anode; the exciton control layer comprises a first hole transport material and a first electron transport material; the second organic light emitting layer comprises an electron transport type host material and a second doped material; the cathode is provided on the side of the second organic light emitting layer away from the anode; and one of the first doped material and the second doped material is a fluorescence-doped material, and the other is a phosphorescence-doped material.

A white organic light emitting device and an organic light emitting display device using the white organic light emitting device stably implement white light in a tandem-type top emission structure through uniform lifespans according to emitted colors of light despite driving of the white organic light emitting device for a long time.

A compound represented by the following formula (1):

##STR00001##

wherein R.sup.1 to R.sup.14, L.sup.1 to L.sup.3, p, q, r, n, and X.sup.1 are defined in the description.

A display device includes: a substrate; a first insulating layer disposed on the substrate and that includes an inorganic insulating material; an oxide semiconductor layer disposed on the first insulating layer; a second insulating layer disposed on the oxide semiconductor layer and that includes an inorganic insulating material; and a third insulating layer disposed on a gate electrode disposed on the second insulating layer and that includes an inorganic insulating material. The oxide semiconductor layer includes a first conductive region, a second conductive region, and a channel region located between the first conductive region and the second conductive region, and a value in the channel region of the oxide semiconductor layer of HC according to equation (1) is less than 30%.