Abstract: A light-emitting element with high emission efficiency. The light-emitting element includes a first organic compound, a second organic compound, and a guest material. The LUMO level of the first organic compound is lower than the LUMO level of the second organic compound. The HOMO level of the first organic compound is lower than the HOMO level of the second organic compound. The HOMO level of the guest material is higher than the HOMO level of the second organic compound. The energy difference between the LUMO level of the guest material and the HOMO level of the guest material is larger than the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound. The guest material has a function of converting triplet excitation energy into light emission. The first organic compound and the second organic compound form an exciplex.

Abstract: An organic compound with an electron-injection property and low water solubility is provided. An organic compound represented by General Formula (G1) is provided. In General Formula (G1), Ar is an aromatic skeleton represented by General Formula (Ar-1); L represents an alkylene group or an arylene group; n represents an integer of 0 to 3; m represents an integer of 1 to 4; and each of R1 to R12 independently represents hydrogen or an alkyl group. In General Formula (Ar-1), each of rings A, B, C, and D independently represents a benzene ring, a naphthalene ring, or a phenanthrene ring; any m carbon atoms on the rings A, B, C, and D each include a bond in General Formula (G1); X1 represents C, Si, or Ge; and ai represents a single bond, O, S, C including a substituent, Si including a substituent, or Ge including a substituent.

Abstract: A display apparatus having a function of emitting visible light and infrared light and a light detection function is provided. The display apparatus includes a first light-emitting device, a second light-emitting device, and a light-receiving device in a display portion. The first light-emitting device emits both visible light and infrared light and the second light-emitting device emits visible light. The light-receiving device has a function of absorbing at least part of visible light and infrared light. The first light-emitting device includes a first pixel electrode, a first light-emitting layer, a second light-emitting layer, and a common electrode. The second light-emitting device includes a second pixel electrode, a third light-emitting layer, and the common electrode. The light-receiving device includes a third pixel electrode, an active layer, and the common electrode. The first light-emitting layer includes a light-emitting material emitting infrared light.

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: 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: An electronic device with high outcoupling efficiency or a high light-trapping effect is provided. The electronic device includes a first layer and a second layer between a first electrode and a second electrode, the first layer is included between the first electrode and the second layer, the first layer includes a first organic compound and a first substance, the refractive index of a thin film of the first organic compound is higher than or equal to 1 and lower than or equal to 1.75, the first substance has an electron-accepting property, and the second layer has a function of emitting or absorbing light.

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: 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: To provide a light-emitting element with high emission efficiency and low driving voltage. The light-emitting element includes a guest material and a host material. A LUMO level of the guest material is lower than a LUMO level of the host material. An energy difference between the LUMO level and a HOMO level of the guest material is larger than an energy difference between the LUMO level and a HOMO level of the host material. The guest material has a function of converting triplet excitation energy into light emission. An energy difference between the LUMO level of the guest material and the HOMO level of the host material is larger than or equal to energy of light emission of the guest material.

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: 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: Provided is a light-emitting element which has an anode, a light-emitting layer over the anode, an electron-transport layer over and in contact with the light-emitting layer, an electron-injection layer over and in contact with the electron-transport layer, and a cathode over and in contact with the electron-injection layer. The light-emitting layer has an electron-transport property, and the electron-transport layer includes an anthracene derivative. The light-emitting layer further includes a phosphorescent substance. This device structure allows the formation of a highly efficient blue-emissive light-emitting element even though the phosphorescent substance has higher triplet energy than the anthracene derivative which directly contacts with the light-emitting layer.

Abstract: A display device that has a function of emitting visible light and infrared light and a function of detecting light. The display device is a display device including a first light-emitting device, a second light-emitting device, and a light-receiving device, in a display portion. The first light-emitting device includes a first pixel electrode, a first optical adjustment layer, a first light-emitting layer, a second light-emitting layer, and a common electrode. The second light-emitting device includes a second pixel electrode, a second optical adjustment layer, the first light-emitting layer, the second light-emitting layer, and the common electrode. The light-receiving device includes a third pixel electrode, an active layer, and the common electrode. The active layer includes an organic compound. The first light-emitting device emits infrared light emitted by the first light-emitting layer. The second light-emitting device emits visible light emitted by the second light-emitting layer.

Abstract: A light-emitting element having low driving voltage and high emission efficiency is provided. In the light-emitting element, a combination of a guest material and a host material forms an exciplex. The guest material is capable of converting triplet excitation energy into light emission. Light emission from the light-emitting layer includes light emission from the guest material and light emission from the exciplex. The percentage of the light emission from the exciplex to the light emission from the light-emitting layer is greater than 0 percent and less than or equal to 60 percent. The energy after subtracting the energy of light emission from the exciplex from the energy of light emission from the guest material is greater than 0 eV and less than or equal to 0.23 eV.

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: A light-emitting device with high outcoupling efficiency is provided. In the light-emitting device including a light-emitting layer between a pair of electrodes, a low refractive index layer containing an organic compound and an inorganic compound is provided between the light-emitting layer and an anode or between the light-emitting layer and a cathode, and the low refractive index layer has a refractive index of less than or equal to 1.80 at a wavelength of light extracted from the light-emitting layer.

Abstract: A light-emitting element with high emission efficiency. The light-emitting element includes a first organic compound, a second organic compound, and a guest material. The LUMO level of the first organic compound is lower than the LUMO level of the second organic compound. The HOMO level of the first organic compound is lower than the HOMO level of the second organic compound. The HOMO level of the guest material is higher than the HOMO level of the second organic compound. The energy difference between the LUMO level of the guest material and the HOMO level of the guest material is larger than the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound. The guest material has a function of converting triplet excitation energy into light emission. The first organic compound and the second organic compound form an exciplex.