Abstract: A novel light-emitting device that is highly convenient, useful, or reliable is provided. The light-emitting device includes a first electrode, a second electrode, and a first layer. The first layer is positioned between the first electrode and the second electrode. The first layer includes a light-emitting material, a first organic compound, and a first material. The light-emitting material has a function of emitting fluorescent light. The absorption spectrum of the light-emitting material has the longest-wavelength edge at a first wavelength. The first organic compound has a function of converting triplet excitation energy into light emission. The spectrum of the emitted light has the shortest-wavelength edge at a second wavelength. The second wavelength is positioned at a wavelength shorter than the first wavelength. The first organic compound includes a first substituent R1. The first substituent R1 is any of an alkyl group, a substituted or unsubstituted cycloalkyl group, and a trialkylsilyl group.

Abstract: A small light-emitting device is provided. A light-emitting device which is less likely to produce a shadow is provided. A structure including a switching circuit for supplying a pulsed constant current and a light-emitting panel supplied with the pulsed constant current has been conceived.

Abstract: A light-emitting element having high emission efficiency is provided. The light-emitting element includes a first organic compound, a second organic compound, and a third organic compound. The first organic compound has a function of converting triplet excitation energy into light emission. The second organic compound is preferably a TADF material. The third organic compound is a fluorescent compound. Light emitted from the light-emitting element is obtained from the third organic compound. Triplet excitation energy in a light-emitting layer is transferred to the third organic compound by reverse intersystem crossing caused by the second organic compound or through the first organic compound.

Abstract: A light-emitting element with high emission efficiency and high reliability is provided. The light-emitting element includes a host material and a guest material in a light-emitting layer. The host material has a function of converting triplet excitation energy into light emission and the guest material emits fluorescence. The molecular structure of the guest material is a structure including a luminophore and protecting groups, and five or more protecting groups are included in one molecule of the guest material. The introduction of the protecting groups into the molecule inhibits energy transfer of triplet excitation energy by the Dexter mechanism from the host material to the guest material. As the protecting group, an alkyl group or a branched-chain alkyl group is used.

Abstract: A novel light-emitting device with a microcavity structure which can improve the emission efficiency compared to the conventional one is provided. In a light-emitting device with a microcavity structure that emits light in a near-infrared range, reflectance of one or both of a first electrode (reflective electrode) and a second electrode (semi-transmissive and semi-reflective electrode) with respect to light in a near-infrared range (e.g., light with a wavelength of 850 nm) is higher than the reflectance thereof with respect to light in a visible light range (greater than or equal to 400 nm and less than 750 nm).

Abstract: A novel light-emitting device that is highly convenient, useful, or reliable is provided. The light-emitting device includes an anode over a cathode with an EL layer sandwiched therebetween. The EL layer includes at least a light-emitting layer and an oxidation-resistant layer over the light-emitting layer. The EL layer has a side surface. The light-emitting device includes a block layer in contact with a top surface and the side surface of the EL layer. The cathode is in contact with the side surface of the EL layer with the block layer therebetween. The block layer includes a heterocyclic compound. In the light-emitting device with the above structure, the oxidation-resistant layer may include any one or a plurality of oxides of metals belonging to Group 4 to Group 8 of the periodic table and an organic compound having an electron-withdrawing group.

Abstract: A light-emitting device with high emission efficiency and reliability is provided. The light-emitting device includes a fluorescent light-emitting layer and a phosphorescent light-emitting layer. A host material used in the fluorescent light-emitting layer has a function of converting triplet excitation energy into light emission and a guest material used in the fluorescent light-emitting layer emits fluorescence. The guest material has a molecular structure including a luminophore and a protecting group, and one molecule of the guest material includes five or more protecting groups. The introduction of the protecting groups into the molecule inhibits transfer of triplet excitation energy from the host material to the guest material by the Dexter mechanism. An alkyl group or a branched-chain alkyl group is used as the protecting group.

Abstract: A novel compound is provided. The novel compound is represented by General Formula (G1). In General Formula (G1), A represents a substituted or unsubstituted condensed aromatic ring having 10 to 30 carbon atoms or a substituted or unsubstituted condensed heteroaromatic ring having 10 to 30 carbon atoms, and R1 represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms. Each of Y1 and Y2 independently represents a cycloalkyl group having a bridge structure and having 7 to 10 carbon atoms.

Abstract: A light-emitting device with a high resolution and high efficiency is provided. The light-emitting device includes a first EL layer, an intermediate layer, and a second EL layer between first and second electrodes. The first EL layer is provided between the first electrode and the intermediate layer, and the second EL layer is provided between the second electrode and the intermediate layer. Side surfaces of the first EL layer, the intermediate layer, and the second EL layer are substantially aligned. The first EL layer includes a layer having an electron-transport property. The intermediate layer is provided in contact with the layer having an electron-transport property. The intermediate layer includes a first organic compound and an alkali metal or a compound of an alkali metal. The layer having an electron-transport property includes a second organic compound. The second organic compound has a higher glass transition temperature than the first organic compound.

Abstract: A high-resolution or high-definition display device is provided. The display device includes a first light-emitting device and a second light-emitting device. The first light-emitting device includes a first pixel electrode, a first hole-injection layer, a first hole-transport layer, a first light-emitting layer, a first electron-transport layer, a second electron-transport layer, and a common electrode that are stacked in this order. The second light-emitting device includes a second pixel electrode, a second hole-injection layer, a second hole-transport layer, a second light-emitting layer, a third electron-transport layer, a second electron-transport layer, and a common electrode that are stacked in this order. The first light-emitting device and the second light-emitting device have a function of emitting light of different colors from each other.

Abstract: A novel light-emitting device that is highly convenient, useful, or reliable is provided. A light-emitting device including a second electrode over a first electrode with an EL layer sandwiched therebetween is provided. The EL layer includes a light-emitting layer and an oxidation-resistant layer over the light-emitting layer. The EL layer includes a side surface. The light-emitting device includes a block layer in contact with a top surface and the side surface of the EL layer. The second electrode is in contact with the side surface of the EL layer through the block layer. The oxidation-resistant layer includes any one or a plurality of oxides of metals belonging to Group 4 to Group 8 of the periodic table and an organic compound having an electron-withdrawing group.

Abstract: A light-emitting apparatus with low power consumption is provided. A light-emitting apparatus including a first light-emitting device and a first color conversion layer. The first light-emitting device includes an anode, a cathode, and an EL layer positioned between the anode and the cathode. The EL layer includes a layer including a material with a refractive index lower than or equal to 1.75 at 467 nm. The first color conversion layer includes a first substance capable of emission by absorbing light. Light emitted from the first light-emitting device enters the first color conversion layer.

Abstract: A light-emitting device is provided. The light-emitting device includes an intermediate layer, a first light-emitting unit, and a second light-emitting unit. The intermediate layer includes a region interposed between the first light-emitting unit and the second light-emitting unit. The intermediate layer has a function of supplying an electron to one of the first light-emitting unit and the second light-emitting unit and supplying a hole to the other. The first light-emitting unit includes a first light-emitting layer, the first light-emitting layer includes a first light-emitting material, the second light-emitting unit includes a second light-emitting layer, the second light-emitting layer includes a second light-emitting material, the second light-emitting layer has a first distance from the first light-emitting layer, and the first distance is longer than or equal to 5 nm and shorter than or equal to 65 nm.

Abstract: A light-emitting device with low power consumption is provided. The light-emitting apparatus including a first light-emitting device and a first color conversion layer. The first light-emitting device includes an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer includes a layer including a material with an ordinary refractive index higher than or equal to 1.50 and lower than 1.75 with respect to light with a wavelength longer than or equal to 455 nm and shorter than or equal to 465 nm. The first color conversion layer includes a first substance that absorbs light and emits light. An ordinary refractive index of the first color conversion layer with respect to light with a wavelength longer than or equal to 455 nm and shorter than or equal to 465 nm is higher than or equal to 1.40 and lower than or equal to 2.10. The first color conversion layer is on an optical path of the light emitted from the first light-emitting device to an outside of the light-emitting apparatus.

Abstract: A light-emitting device with high emission efficiency is provided. The light-emitting device includes an anode, a cathode, and an EL layer positioned between the anode and the cathode. The EL layer includes a light-emitting layer and an electron-transport layer; the light-emitting layer includes a light-emitting material; the electron-transport layer includes an organic compound having an electron-transport property and a metal complex of an alkali metal; the ordinary refractive index of the organic compound having an electron-transport property in a peak wavelength of light emitted from the light-emitting material is greater than or equal to 1.50 and less than or equal to 1.75; and the ordinary refractive index of the metal complex of an alkali metal in the peak wavelength of the light emitted from the light-emitting material is greater than or equal to 1.45 and less than or equal to 1.70.

Abstract: An object is to provide a light-emitting element capable of emitting light with a high luminance even at a low voltage, and having a long lifetime. The light-emitting element includes n EL layers between an anode and a cathode (n is a natural number of two or more), and also includes, between m-th EL layer from the anode and (m+1)-th EL layer (m is a natural number, 1?m?n?1), a first layer including a first donor material in contact with the m-th EL layer, a second layer including an electron-transport material and a second donor material in contact with the first layer, and a third layer including a hole-transport material and an acceptor material in contact with the second layer and the (m+1)-th EL layer.

Abstract: A light-emitting element includes an EL layer between a pair of electrodes. The EL layer contains a first compound and a second compound. The first compound is a phosphorescent iridium metal complex having a LUMO level of greater than or equal to ?3.5 eV and less than or equal to ?2.5 eV, and the second compound is an organic compound having a pyrimidine skeleton. The light-emitting element includes an EL layer between a pair of electrodes. The EL layer contains a first compound and a second compound. The first compound is a phosphorescent iridium metal complex having a diazine skeleton, and the second compound is an organic compound having a pyrimidine skeleton.

Abstract: Provided is a light-emitting device with high emission efficiency. Provided is a light-emitting device including an anode, a cathode, and an EL layer positioned therebetween; the EL layer includes a light-emitting layer, a first layer, and a second layer; the first layer is positioned between the anode and the light-emitting layer; the first layer is in contact with the second layer; the second layer contains a monoamine compound having an arylamine structure; a first group, a second group, and a third group are bonded to a nitrogen atom included in the amine in the monoamine compound; the first group is a group including a carbazole structure; the second group is a group including a dibenzofuran structure or a dibenzothiophene structure; the third group includes an aromatic hydrocarbon structure having 6 to 18 carbon atoms or a heteroaromatic hydrocarbon structure having 4 to 26 carbon atoms; and a refractive index of the first layer is lower than a refractive index of the light-emitting layer.

Abstract: Provided is a light-emitting element which includes a light-emitting layer containing a phosphorescent compound, a first organic compound, and a second organic compound between a pair of electrodes. A combination of the first organic compound and the second organic compound forms an exciplex (excited complex). An emission spectrum of the exciplex overlaps with an absorption band located on the longest wavelength side of an absorption spectrum of the phosphorescent compound. A peak wavelength of the emission spectrum of the exciplex is longer than or equal to a peak wavelength of the absorption band located on the longest wavelength side of the absorption spectrum of the phosphorescent compound.

Abstract: A green phosphorescent light-emitting device with a long lifetime is provided. The light-emitting device includes a first electrode, a second electrode, and a light-emitting layer. The light-emitting layer is between the first electrode and the second electrode. The light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent light-emitting substance. The first organic compound includes a heteroaromatic ring skeleton and an aromatic hydrocarbon group. The second organic compound includes a bicarbazole skeleton. The lowest triplet excited level of the first organic compound is derived from only the aromatic hydrocarbon group. The energy of the lowest triplet excited level of the second organic compound is higher than or equal to 2.20 eV and lower than or equal to 2.65 eV.