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: 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 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: 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 novel organic compound that forms an exciplex emitting light with high efficiency is provided. An organic compound with a triarylamine skeleton in which the three aryl groups of the triarylamine skeleton are a p-biphenyl group, a fluoren-2-yl group, and a phenyl group to which a dibenzofuranyl group or a dibenzothiophenyl group is bonded. By the use of the organic compound and an organic compound with an electron-transport property, an exciplex that emits light with extremely high efficiency can be formed.

Abstract: A novel light-emitting device is provided. A light-emitting device with high emission efficiency is provided. A light-emitting device with a long lifetime is provided. A light-emitting device with low driving voltage is provided. The light-emitting device includes an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer includes a hole-injection layer, a light-emitting layer, and an electron-transport layer. The hole-injection layer is positioned between the anode and the light-emitting layer. The electron-transport layer is positioned between the light-emitting layer and the cathode. The hole-injection layer contains a first substance and a second substance. The first substance is an organic compound which has a hole-transport property and a HOMO level higher than or equal to ?5.7 eV and lower than or equal to ?5.4 eV. The second substance exhibits an electron-accepting property with respect to the first substance.

Abstract: A light-emitting element having a long lifetime is provided. A light-emitting element exhibiting high emission efficiency in a high luminance region is provided. A light-emitting element includes a light-emitting layer between a pair of electrodes. The light-emitting layer contains a first organic compound, a second organic compound, and a phosphorescent compound. The first organic compound is represented by a general formula (GO). The molecular weight of the first organic compound is greater than or equal to 500 and less than or equal to 2000. The second organic compound is a compound having an electron-transport property. In the general formula (GO), Ar1 and Ar2 each independently represent a fluorenyl group, a spirofluorenyl group, or a biphenyl group, and Ar3 represents a substituent including a carbazole skeleton.

Abstract: A multicolor light-emitting element using fluorescence and phosphorescence, which has a small number of manufacturing steps owing to a relatively small number of layers to be formed and is advantageous for practical application can be provided. In addition, a multicolor light-emitting element using fluorescence and phosphorescence, which has favorable emission efficiency is provided. A light-emitting element which includes a light-emitting layer having a stacked-layer structure of a first light-emitting layer exhibiting light emission from a first exciplex and a second light-emitting layer exhibiting phosphorescence is provided.

Abstract: A light-emitting element having a long lifetime is provided. A light-emitting element exhibiting high emission efficiency in a high luminance region is provided. A light-emitting element includes a light-emitting layer between a pair of electrodes. The light-emitting layer contains a first organic compound, a second organic compound, and a phosphorescent compound. The first organic compound is represented by a general formula (G0). The molecular weight of the first organic compound is greater than or equal to 500 and less than or equal to 2000. The second organic compound is a compound having an electron-transport property. In the general formula (G0), Ar1 and Ar2 each independently represent a fluorenyl group, a spirofluorenyl group, or a biphenyl group, and Ar3 represents a substituent including a carbazole skeleton.

Abstract: To provide a light-emitting element which uses a fluorescent material as a light-emitting substance and has higher luminous efficiency. To provide a light-emitting element which includes a mixture of a thermally activated delayed fluorescent substance and a fluorescent material. By making the emission spectrum of the thermally activated delayed fluorescent substance overlap with an absorption band on the longest wavelength side in absorption by the fluorescent material in an S1 level of the fluorescent material, energy at an S1 level of the thermally activated delayed fluorescent substance can be transferred to the S1 of the fluorescent material. Alternatively, it is also possible that the S1 of the thermally activated delayed fluorescent substance is generated from part of the energy of a T1 level of the thermally activated delayed fluorescent substance, and is transferred to the S1 of the fluorescent material.

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: 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: A light-emitting element which has low driving voltage and high emission efficiency is provided. The light-emitting element includes, between a pair of electrodes, a hole-transport layer and a light-emitting layer over the hole-transport layer. The light-emitting layer contains a first organic compound having an electron-transport property, a second organic compound having a hole-transport property, and a light-emitting third organic compound converting triplet excitation energy into light emission. A combination of the first organic compound and the second organic compound forms an exciplex. The hole-transport layer contains at least a fourth organic compound whose HOMO level is lower than or equal to that of the second organic compound and a fifth organic compound whose HOMO level is higher than that of the second organic compound.

Abstract: To provide a light-emitting element which uses a fluorescent material as a light-emitting substance and has higher luminous efficiency. To provide a light-emitting element which includes a mixture of a thermally activated delayed fluorescent substance and a fluorescent material. By making the emission spectrum of the thermally activated delayed fluorescent substance overlap with an absorption band on the longest wavelength side in absorption by the fluorescent material in an S1 level of the fluorescent material, energy at an S1 level of the thermally activated delayed fluorescent substance can be transferred to the S1 of the fluorescent material. Alternatively, it is also possible that the S1 of the thermally activated delayed fluorescent substance is generated from part of the energy of a T1 level of the thermally activated delayed fluorescent substance, and is transferred to the S1 of the fluorescent material.

Abstract: A light-emitting element having high emission efficiency is provided. A light-emitting element having a low driving voltage is provided. A novel compound which can be used for a transport layer or as a host material or a light-emitting material of a light-emitting element is provided. A novel compound with a benzofuropyrimidine skeleton is provided. Also provided is a light-emitting element which includes the compound with the benzofuropyrimidine skeleton between a pair of electrodes.

Abstract: A light-emitting element which has low driving voltage and high emission efficiency is provided. The light-emitting element includes, between a pair of electrodes, a hole-transport layer and a light-emitting layer over the hole-transport layer. The light-emitting layer contains a first organic compound having an electron-transport property, a second organic compound having a hole-transport property, and a light-emitting third organic compound converting triplet excitation energy into light emission. A combination of the first organic compound and the second organic compound forms an exciplex. The hole-transport layer contains at least a fourth organic compound whose HOMO level is lower than or equal to that of the second organic compound and a fifth organic compound whose HOMO level is higher than that of the second organic compound.

Abstract: An organic semiconductor element with low driving voltage is provided. The organic semiconductor element includes a first electrode, a second electrode, and a hole-transport layer and an active layer between the first electrode and the second electrode. The hole-transport layer includes a first hole-transport layer and a second hole-transport layer. The first hole-transport layer is closer to the substrate than the second hole-transport layer is. The first hole-transport layer and the second hole-transport layer are in contact with each other. A value obtained by subtracting GSP_slope (mV/nm) of the second hole-transport layer from GSP_slope (mV/nm) of the first hole-transport layer is less than or equal to 10 (mV/nm). Note that GSP_slope (mV/nm) is a parameter represented by V/d when surface potential and thickness of a film are V (mV) and d (nm), respectively.

Abstract: A novel light-emitting device is provided. A light-emitting device with high emission efficiency is provided. A light-emitting device with a long lifetime is provided. A light-emitting device with low driving voltage is provided. The light-emitting device includes an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer includes a hole-injection layer, a light-emitting layer, and an electron-transport layer. The hole-injection layer is positioned between the anode and the light-emitting layer. The electron-transport layer is positioned between the light-emitting layer and the cathode. The hole-injection layer contains a first substance and a second substance. The first substance is an organic compound which has a hole-transport property and a HOMO level higher than or equal to ?5.7 eV and lower than or equal to ?5.4 eV. The second substance exhibits an electron-accepting property with respect to the first substance.

Abstract: A light-emitting element having high emission efficiency is provided. A light-emitting element having a low driving voltage is provided. A novel compound which can be used for a transport layer or as a host material or a light-emitting material of a light-emitting element is provided. A novel compound with a benzofuropyrimidine skeleton is provided. Also provided is a light-emitting element which includes the compound with the benzofuropyrimidine skeleton between a pair of electrodes.

Abstract: An organic semiconductor device with low driving voltage is provided. The light-emitting device includes an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer includes a hole-transport layer and alight-emitting layer. The hole-transport layer is positioned between the anode and the light-emitting layer. The hole-transport layer is not in contact with the anode. The hole-transport layer includes a transport layer material for a light-emitting device and the GSP_slope that is a potential gradient of a surface potential of an evaporated film of the material is higher than or equal to 20 (mV/nm).