Abstract: An object is to provide a light-emitting element with high emission efficiency. The light-emitting element contains first to third organic compounds. The first organic compound has a function of converting triplet excitation energy into light. The second organic compound has a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton. The third organic compound is a fluorescent compound. Light emitted from the light-emitting element is light emitted from the third organic compound that receives excitation energy from the first organic compound or from an exciplex formed by the first and second organic compounds.

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.

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, a first unit, and a first layer. The first unit is positioned between the first electrode and the second electrode and contains a first light-emitting material. The first layer is positioned between the second electrode and the first unit and contains a first organic compound and a second organic compound. The first organic compound has an acid dissociation constant pKa larger than or equal to 8, and the second organic compound has no pyridine ring, no phenanthroline ring, or one phenanthroline ring.

Abstract: An electron-injection organic compound with low solubility in water is provided. An organic compound represented by General Formula (G1) is provided. X represents a group represented by General Formula (X-1) and Y represents a group represented by General Formula (Y-1). Ar represents a heteroaromatic hydrocarbon group having 2 to 30 carbon atoms forming a ring or an aromatic hydrocarbon group having 6 to 30 carbon atoms forming a ring. Each of R1 and R2 independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms, and h represents an integer of 1 to 6. In General Formulae (X-1) and (Y-1), each of R3 to R6 independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms, and m represents an integer of 0 to 4. When m is 0, 1, 3, or 4, n represents an integer of 1 to 5. When m is 2, n represents 1, 2, 4, or 5.

Abstract: A highly reliable and efficient light-emitting device is provided. The light-emitting device includes an organic compound layer between a first electrode and a second electrode. The organic compound layer includes a first EL layer, a second EL layer, and an intermediate layer. The intermediate layer is between the first EL layer and the second EL layer. The intermediate layer includes a mixed layer containing a first organic compound and a second organic compound. The first organic compound has strong basicity with an acid dissociation constant pKa greater than or equal to 8. The second organic compound has an electron-transport property. The LUMO level of the first organic compound is higher than the LUMO level of the second organic compound. The HOMO level of the first organic compound is higher than the HOMO level of the second organic compound.

Abstract: Provided is a novel display apparatus that is highly convenient, useful, or reliable. The display apparatus includes a blue-light-emitting device and a green-light-emitting device. The blue-light-emitting device includes a first unit, a second unit, and a first intermediate layer; and the first unit and the second unit each emit blue light. The first intermediate layer is interposed between the first unit and the second unit and supplies electrons to one of them and holes to the other; the second unit includes a first layer containing a first light-emitting material; and the first layer has its central plane a first distance away from a first reflective film. The green-light-emitting device includes a third unit, a fourth unit, and a second intermediate layer; and the third unit and the fourth unit each emit green light.

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 element containing a light-emitting material and having high light emission efficiency is provided. The light-emitting element includes a host material and a guest material. The host material includes at least a first molecule and a second molecule having the same molecular structure. The guest material has a function of exhibiting fluorescence or converting triplet excitation energy into light emission. The first molecule and the second molecule each include a first skeleton, a second skeleton, and a third skeleton, and the first skeleton and the second skeleton are bonded to each other through the third skeleton. The first skeleton includes at least one of a ?-electron rich heteroaromatic skeleton and an aromatic amine skeleton and the second skeleton includes a ?-electron deficient heteroaromatic skeleton. The first molecule and the second molecule have a function of forming an excited complex.

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 highly efficient and highly reliable light-emitting device is provided. The light-emitting device includes an organic compound layer between a pair of electrodes. The organic compound layer includes a light-emitting layer, the light-emitting layer includes a first organic compound, a second organic compound, and a light-emitting substance, the first organic compound contains deuterium, and in a PL measurement of a mixed layer of the first organic compound and the second organic compound, a spectrum of an exciplex is observed at room temperature, and a spectrum of the exciplex is not observed at a temperature in a temperature range of 4 K to 80 K, inclusive.

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 absorp-tion spectrum of the phosphorescent compound.

Abstract: A light-emitting device with a high resolution and favorable characteristics manufactured by a photolithography method is provided. The light-emitting apparatus includes first and second light-emitting devices. The first and second light-emitting devices are adjacent to each other. The first light-emitting device includes a first EL layer A and a second EL layer. The second light-emitting device includes a first EL layer B and the second EL layer. The first EL layer A and the first EL layer B are independent of each other. The second EL layer is shared by the first and second light-emitting devices. An end surface of the first EL layer A on the first EL layer B side and an end surface of the first EL layer B on the first EL layer A side face each other. The first EL layer A includes a light-emitting layer. The light-emitting layer includes a light-emitting material, first and second organic compounds. The first organic compound is an organic compound having an electron-transport property.

Abstract: To provide a light-emitting device having high efficiency and high reliability. The light-emitting device includes a first electrode, a second electrode, and an organic compound layer; the organic compound layer is between the first electrode and the second electrode; the organic compound layer includes a first light-emitting unit, a second light-emitting unit, and an intermediate layer; the intermediate layer is between the first light-emitting unit and the second light-emitting unit; the intermediate layer includes a mixed layer containing a first organic compound and a second organic compound; the first organic compound is strongly basic; the second organic compound has an electron-transport property; and the first organic compound has a higher LUMO level than the second organic compound.

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, a first unit, a second unit, and a first intermediate layer. The first unit is between the first electrode and the second electrode. The first unit contains a first light-emitting material. The second unit is between the first unit and the second electrode. The second unit contains a second light-emitting material. The first intermediate layer is between the first unit and the second unit. The first intermediate layer contains a first organic compound and a second organic compound. The first organic compound has an acid dissociation constant pKa larger than or equal to 8. The second organic compound has an acid dissociation constant pKa smaller than 4.

Abstract: A tandem light-emitting device that can be used in a high-resolution display apparatus is provided. The light-emitting device includes a first electrode, a second electrode, and an organic compound layer. The organic compound layer is positioned between the first electrode and the second electrode; the organic compound layer includes a first light-emitting unit, a second light-emitting unit, and an intermediate layer; the intermediate layer is positioned between the first light-emitting unit and the second light-emitting unit; the first light-emitting unit is positioned between the first electrode and the intermediate layer; the first light-emitting unit includes a first light-emitting layer and a first electron-transport layer; the first electron-transport layer is in contact with the intermediate layer; the intermediate layer is configured to block holes moving from the first electrode side to the second electrode side; and the first electron-transport layer is a layer having a bipolar property.

Abstract: A novel compound is provided. The novel compound is represented by General Formula (G1). Each of A1 and A2 independently represents a substituted or unsubstituted condensed aromatic ring, a substituted or unsubstituted condensed heteroaromatic ring, or a structure represented by Formula (Z-1) or (Z-2); and each of Z1 and Z2 independently has a structure represented by Formula (Z-1) or (Z-2), Each of X1 and X2 independently represents any one of an alkyl group, a cycloalkyl group, a substituted or unsubstituted cycloalkyl group having a bridge structure, and a trialkylsilyl group. Each of Ar1 and Ar2 independently represents a substituted or unsubstituted aromatic hydrocarbon group, and at least one of Ar1 and Ar2 includes the same substituent as X1. Each of R1 to R16 independently represents any one of hydrogen, an alkyl group, a substituted or unsubstituted cycloalkyl group, a trialkylsilyl group, and a substituted or unsubstituted aryl group.

Abstract: A novel display device that is highly convenient, useful, or reliable is provided. The display apparatus includes a first light-emitting device, a second light-emitting device, and a first layer. The first light-emitting device includes a first electrode, a second electrode, a first unit between the first electrode and the second electrode, and a second layer between the first electrode and the first unit. The first unit includes a first light-emitting material. The second light-emitting device includes a third electrode, a fourth electrode, a second unit between the third electrode and the fourth electrode, and a third layer between the third electrode and the second unit. The second unit includes a second light-emitting material. The first layer is between the first electrode and the second layer and between the third electrode and the third layer, and overlaps with a first gap between the first electrode and the third electrode.

Abstract: A novel organometallic complex and a novel light-emitting device that are highly useful or reliable are provided. The organometallic complex represented by General Formula (G1) is provided. Note that R1, R2, and R4 to R22 each independently represent hydrogen (including deuterium), an alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 18 carbon atoms, at least one of R2 and R4 represents an alkyl group having 1 to 10 carbon atoms, and any one or more of R18 to R22 represent an alkyl group having 3 to 10 carbon atoms or a substituted or unsubstituted aryl group having 6 to 18 carbon atoms.

Abstract: The light-emitting device includes a first electrode, a second electrode, and an organic compound layer between the first electrode and the second electrode. The organic compound layer includes a first light-emitting unit, an intermediate layer, and a second light-emitting unit in this order from the first electrode side. The first light-emitting unit includes a first light-emitting layer, and the second light-emitting unit includes a second light-emitting layer. The intermediate layer includes a first layer, a second layer, and a third layer in this order from the first electrode side, with the second layer being in contact with the first layer and the third layer. The spin density of the first layer is lower than or equal to 1×1017 spins/cm3. The LUMO level of a material included in the second layer is greater than or equal to ?4.30 eV and less than or equal to ?3.00 eV.

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.