Light-emitting element, display module, lighting module, light-emitting device, display device, electronic appliance, and lighting device
First Claim
1. A light-emitting element comprising:
- a pair of electrodes; and
an EL layer between the pair of electrodes,wherein the EL layer comprises a first light-emitting layer, a second light-emitting layer, and a first layer between the first light-emitting layer and the second light-emitting layer,wherein an emission spectrum of the first light-emitting layer is in a shorter wavelength region than an emission spectrum of the second light-emitting layer,wherein the first light-emitting layer comprises a fluorescent substance and a host material,wherein the fluorescent substance emits light in the first light-emitting layer,wherein the second light-emitting layer comprises a substance capable of converting triplet excitation energy into light emission,wherein a singlet excited level of the host material is higher than a singlet excited level of the fluorescent substance, andwherein a triplet excited level of the host material is lower than a triplet excited level of the fluorescent substance.
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Accused Products
Abstract
An object of one embodiment of the present invention is to provide a multicolor light-emitting element that utilizes fluorescence and phosphorescence and is advantageous for practical application. The light-emitting element has a stacked-layer structure of a first light-emitting layer containing a host material and a fluorescent substance, a separation layer containing a substance having a hole-transport property and a substance having an electron-transport property, and a second light-emitting layer containing two kinds of organic compounds that form an exciplex and a substance that can convert triplet excitation energy into luminescence. Note that a light-emitting element in which light emitted from the first light-emitting layer has an emission spectrum peak on the shorter wavelength side than an emission spectrum peak of the second light-emitting layer is more effective.
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Citations
21 Claims
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1. A light-emitting element comprising:
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a pair of electrodes; and an EL layer between the pair of electrodes, wherein the EL layer comprises a first light-emitting layer, a second light-emitting layer, and a first layer between the first light-emitting layer and the second light-emitting layer, wherein an emission spectrum of the first light-emitting layer is in a shorter wavelength region than an emission spectrum of the second light-emitting layer, wherein the first light-emitting layer comprises a fluorescent substance and a host material, wherein the fluorescent substance emits light in the first light-emitting layer, wherein the second light-emitting layer comprises a substance capable of converting triplet excitation energy into light emission, wherein a singlet excited level of the host material is higher than a singlet excited level of the fluorescent substance, and wherein a triplet excited level of the host material is lower than a triplet excited level of the fluorescent substance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A light-emitting element comprising:
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a pair of electrodes; and an EL layer between the pair of electrodes, wherein the EL layer comprises a first light-emitting layer, a second light-emitting layer, and a first layer between the first light-emitting layer and the second light-emitting layer, wherein an emission spectrum of the first light-emitting layer is in a shorter wavelength region than an emission spectrum of the second light-emitting layer, wherein the first light-emitting layer comprises a fluorescent substance and a host material, wherein the fluorescent substance emits light in the first light-emitting layer, wherein the fluorescent substance comprises a pyrene skeleton, wherein the host material comprises a condensed aromatic ring, and wherein the second light-emitting layer comprises a substance capable of converting triplet excitation energy into light emission. - View Dependent Claims (19, 21)
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18. A light-emitting element comprising:
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a pair of electrodes; and an EL layer between the pair of electrodes, wherein the EL layer comprises a first light-emitting layer, a second light-emitting layer, and a first layer between the first light-emitting layer and the second light-emitting layer, wherein an emission spectrum of the first light-emitting layer is in a shorter wavelength region than an emission spectrum of the second light-emitting layer, wherein the first light-emitting layer comprises a fluorescent substance and a host material, wherein the fluorescent substance emits light in the first light-emitting layer, wherein the fluorescent substance comprises a pyrene skeleton, wherein the host material comprises a condensed aromatic ring, wherein the second light-emitting layer comprises a substance, a first organic compound, and a second organic compound and, wherein the first organic compound and the second organic compound form an exciplex. - View Dependent Claims (20)
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Specification