Abstract: A light-emitting device with high reliability is provided. The light-emitting device includes a first electrode, a second electrode, and an EL layer. The EL layer is positioned between the first electrode and the second electrode. The EL layer includes a light-emitting layer and an electron-injection layer. The electron-injection layer contains a metal or an oxide of the metal, a first organic compound, and a second organic compound. The first organic compound includes a first ?-electron deficient heteroaromatic ring with an electron-donating group. The second organic compound includes a second ?-electron deficient heteroaromatic ring. The LUMO level of the second organic compound is lower than that of the first organic compound by 0.20 eV or more.

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: A light-emitting device with favorable characteristics is provided. In a plurality of light-emitting devices each including an organic compound layer formed over the same insulating surface, the organic compound layer includes a first light-emitting layer, a second light-emitting layer, and an intermediate layer. The intermediate layer includes a first layer. The first layer includes a metal or metal compound, a first organic compound, and a second organic compound. The first organic compound includes a ?-electron deficient heteroaromatic ring. The second organic compound includes two or more heteroaromatic rings that are bonded or condensed to each other and include three or more heteroatoms in total. The second organic compound interacts with the metal or metal compound by two or more of the three or more heteroatoms as a multidentate ligand.

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: As a novel substance having a novel skeleton, an organometallic complex with high emission efficiency which achieves improved color purity by a reduction of half width of an emission spectrum is provided. One embodiment of the present invention is an organometallic complex in which a ?-diketone and a six-membered heteroaromatic ring including two or more nitrogen atoms inclusive of a nitrogen atom that is a coordinating atom are ligands. In General Formula (G1), X represents a substituted or unsubstituted six-membered heteroaromatic ring including two or more nitrogen atoms inclusive of a nitrogen atom that is a coordinating atom. Further, R1 to R4 each represent a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms.

Abstract: A light-emitting device with a low driving voltage and favorable current efficiency which can be used for a high-resolution display apparatus is provided. A tandem light-emitting device that is fabricated through a photolithography process and includes a plurality of light-emitting units and an intermediate layer between the light-emitting units is provided. The intermediate layer includes a first region including a metal or a metal oxide, a first organic compound including a first ?-electron deficient heteroaromatic ring with an electron-donating group, and a second organic compound including a second ?-electron deficient heteroaromatic ring. The LUMO level of the second organic compound is lower than that of the first organic compound by greater than or equal to 0.30 eV.

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 device with low driving voltage is provided. The organic semiconductor device includes a layer containing an organic compound between a pair of electrodes. The layer containing an organic compound includes a hole-transport region. The hole-transport region includes a first layer and a second layer. The first layer is positioned between the anode and the second layer. When a potential gradient of a surface potential of an evaporated film is set as GSP (mV/nm), a value obtained by subtracting GSP of an organic compound in the second layer from GSP of an organic compound in the first layer is less than or equal to 20 (mV/nm).

Abstract: Alight-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 device that can be used in a high-resolution display apparatus and has a low driving voltage and high current efficiency is provided. A tandem light-emitting device is fabricated through a photolithography process and includes a plurality of light-emitting units and an intermediate layer therebetween. The intermediate layer includes a layer that includes a metal oxide and an organic compound having a phenanthroline ring with an electron-donating group. The layer of the intermediate layer is in contact with a light-emitting unit on the anode side.

Abstract: A light-emitting element that includes a fluorescent material and has a high emission efficiency is provided. A light-emitting element in which a delayed fluorescence component due to TTA accounts for a high proportion of emissive components is provided. A novel light-emitting device with a high emission efficiency and a low power consumption is provided. A light-emitting element includes an anode, a cathode, and an EL layer. The EL layer includes a light-emitting layer including a host material and an electron-transport layer including a first material in contact with the light-emitting layer. The LUMO level of the first material is lower than that of the host material. The proportion of a delayed fluorescence component due to TTA is greater than or equal to 10 percent of the light emission from the EL layer. The proportion of the delayed fluorescence component due to TTA may be greater than or equal to 15 percent of the light emission.

Abstract: A novel light-emitting device is provided. Alternatively, a light-emitting device with high emission efficiency is provided. Alternatively, a light-emitting device having a long lifetime is provided. Alternatively, a light-emitting device having low driving voltage is provided. A light-emitting device including an EL layer including a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in this order from the anode side is provided. The first layer includes a first organic compound and a second organic compound. The fourth layer includes a seventh organic compound. The first organic compound exhibits an electron-accepting property with respect to the second organic compound. The HOMO level of the second organic compound is from ?5.7 eV to ?5.4 eV. The HOMO level of the seventh organic compound is ?6.0 eV or higher.

Abstract: As a novel substance having a novel skeleton, an organometallic complex with high emission efficiency which achieves improved color purity by a reduction of half width of an emission spectrum is provided. One embodiment of the present invention is an organometallic complex in which a ?-diketone and a six-membered heteroaromatic ring including two or more nitrogen atoms inclusive of a nitrogen atom that is a coordinating atom are ligands. In General Formula (G1), X represents a substituted or unsubstituted six-membered heteroaromatic ring including two or more nitrogen atoms inclusive of a nitrogen atom that is a coordinating atom. Further, R1 to R4 each represent a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms.

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, and the first unit is held between the first electrode and the second electrode and includes a second layer, a third layer, and a fourth layer. The second layer is held between the third layer and the fourth layer, and the second layer contains a light-emitting material. The fourth layer is held between the second layer and the second electrode and contains a first organic compound. The first organic compound has a ?-electron deficient heteroaromatic ring skeleton and a ?-electron rich heteroaromatic ring skeleton and has a HOMO level higher than or equal to ?6.0 eV and lower than or equal to ?5.6 eV. The first layer is held between the first electrode and the first unit, is in contact with the first electrode, and contains a second organic compound and a third organic compound.

Abstract: To provide a light-emitting device with favorable characteristics. A plurality of light-emitting devices are over one insulating surface. Each of the plurality of light-emitting devices includes a first electrode, a second electrode, and an organic compound layer between the first electrode and the second electrode. The first electrodes of the plurality of light-emitting devices are separate from each other. The second electrode is shared by the plurality of light-emitting devices. The organic compound layer includes a first light-emitting layer, a second light-emitting layer, and an intermediate layer between the first light-emitting layer and the second light-emitting layer. Contours of the first light-emitting layer, the intermediate layer, and the second light-emitting layer are aligned or substantially aligned with each other in each of the plurality of light-emitting devices. The intermediate layer includes a first layer.

Abstract: A light-emitting device with high efficiency and high reliability. The light-emitting device includes an organic compound layer between a first electrode and a 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 intermediate layer includes an organic compound. A peak current of electron oxidation is detected and a peak current of electron reduction is not detected in the case where the organic compound is measured by CV at a scan rate greater than or equal to 1 V/s and less than or equal to 100 V/s.

Abstract: A tandem light-emitting device that can be suitably used for a high-resolution display device is provided. The light-emitting device includes a first electrode, a second electrode facing the first electrode, a first light-emitting layer, a second light-emitting layer, and a first layer. The first light-emitting layer and the second light-emitting layer are between the first electrode and the second electrode. The first layer is between the first light-emitting layer and the second light-emitting layer. GSP_slope (mV/nm) of the first layer and GSP_slope (mV/nm) of the first light-emitting layer are denoted by signs of opposite polarities. Note that the GSP_slope (mV/nm) is a parameter represented by V/d when a surface potential and a thickness of a film are represented by V (mV) and d (nm), respectively.

Abstract: A novel light-emitting device is provided. Alternatively, a light-emitting device with high emission efficiency is provided. Alternatively, a light-emitting device having a long lifetime is provided. Alternatively, a light-emitting device having low driving voltage is provided. A light-emitting device including an EL layer including a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in this order from the anode side is provided. The first layer includes a first organic compound and a second organic compound. The fourth layer includes a seventh organic compound. The first organic compound exhibits an electron-accepting property with respect to the second organic compound. The HOMO level of the second organic compound is from ?5.7 eV to ?5.4 eV. The HOMO level of the seventh organic compound is ?6.0 eV or higher.

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: 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.