Abstract: To provide a light-emitting element with an improved reliability, a light-emitting element with a high current efficiency (or a high quantum efficiency), and a novel dibenzo[f,h]quinoxaline derivative that is favorably used in a light-emitting element which is one embodiment of the present invention. A light-emitting element includes an EL layer between an anode and a cathode. The EL layer includes a light-emitting layer; the light-emitting layer contains a first organic compound having an electron-transport property and a hole-transport property, a second organic compound having a hole-transport property, and a light-emitting substance; the combination of the first organic compound and the second organic compound forms an exciplex; the HOMO level of the first organic compound is lower than the HOMO level of the second organic compound; and a difference between the HOMO level of the first organic compound and the HOMO level of the second organic compound is less than or equal to 0.4 eV.

Abstract: A light-emitting element which includes a plurality of light-emitting layers between a pair of electrodes and has low driving voltage and high emission efficiency is provided. A light-emitting element including first to third light-emitting layers between a cathode and an anode is provided. The first light-emitting layer includes a first phosphorescent material and a first electron-transport material; the second light-emitting layer includes a second phosphorescent material and a second electron-transport material; the third light-emitting layer includes a fluorescent material and a third electron-transport material; the first to third light-emitting elements are provided in contact with an electron-transport layer positioned on a cathode side; and a triplet excitation energy level of a material included in the electron-transport layer is lower than triplet excitation energy levels of the first electron-transport material and the second electron-transport material.

Abstract: A furopyrazine derivative that is a novel organic compound is provided. The organic compound has a furopyrazine skeleton and is represented by General Formula (G1). In General Formula (G1), Q represents oxygen or sulfur, Ar1 represents a substituted or unsubstituted condensed aromatic ring, R1 and R2 independently represent hydrogen or a group having 1 to 100 total carbon atoms, and at least one of R1 and R2 has a hole-transport skeleton.

Abstract: A multicolor light-emitting element that utilizes fluorescence and phosphorescence and is advantageous for practical application is provided. The light-emitting element has a stacked-layer structure of a first light-emitting layer containing a host material and a fluorescent substance and a second light-emitting layer containing two kinds of organic compounds and a substance that can convert triplet excitation energy into luminescence. Note that light emitted from the first light-emitting layer has an emission peak on the shorter wavelength side than light emitted from the second light-emitting layer.

Abstract: An object is to provide a light-emitting element which uses a plurality of kinds of light-emitting dopants and has high emission efficiency. In one embodiment of the present invention, a light-emitting device, a light-emitting module, a light-emitting display device, an electronic device, and a lighting device each having reduced power consumption by using the above light-emitting element are provided. Attention is paid to Forster mechanism, which is one of mechanisms of intermolecular energy transfer. Efficient energy transfer by Forster mechanism is achieved by making an emission wavelength of a molecule which donates energy overlap with the longest-wavelength-side local maximum peak of a graph obtained by multiplying an absorption spectrum of a molecule which receives energy by a wavelength raised to the fourth power.

Abstract: To provide a novel arylamine compound with a low refractive index. The provided arylamine compound includes at least one aromatic group. The aromatic group includes a first benzene ring, a second benzene ring, a third benzene ring, and at least three alkyl groups. The first benzene ring, the second benzene ring, and the third benzene ring are directly bonded in this order. The first benzene ring is bonded to nitrogen of amine. The first benzene ring may further include a substituted or unsubstituted phenyl group. The second benzene ring or the third benzene ring may further include an alkylated phenyl group. Each of first positions and third positions of two or more of the first to third benzene rings is independently bonded to another benzene ring, a benzene ring of the alkylated phenyl group, any of the at least three alkyl groups, or the nitrogen of the amine.

Abstract: The invention relates to: a light-emitting device which includes a first flexible substrate having a first electrode, a light-emitting layer over the first electrode, and a second electrode with a projecting portion over the light-emitting layer and a second flexible substrate having a semiconductor circuit and a third electrode electrically connected to the semiconductor circuit, in which the projecting portion of the second electrode and the third electrode are electrically connected to each other; a method for manufacturing the light-emitting device; and a cellular phone which includes a housing incorporating the light-emitting device and having a longitudinal direction and a lateral direction, in which the light-emitting device is disposed on a front side and in an upper portion in the longitudinal direction of the housing.

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 a light-emitting layer including a guest, an n-type host and a p-type host between a pair of electrodes, where the difference between the energy difference between a triplet excited state and a ground state of the n-type host (or p-type host) and the energy difference between a triplet excited state and a ground state of the guest is 0.15 eV or more. Alternatively, in such a light-emitting element, the LUMO level of the n-type host is higher than the LUMO level of the guest by 0.1 eV or more, or the HOMO level of the p-type host is lower than the HOMO level of the guest by 0.1 eV or more.

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 high emission efficiency and high reliability is provided. The light-emitting device 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 guest material has a molecular structure including a luminophore and protecting groups, and five or more protecting groups are included in one molecule of the guest materials. When the protecting groups are introduced into the molecule, triplet excitation energy transfer from the host material to the guest material by the Dexter mechanism is inhibited. As the protecting group, an alkyl group or a branched-chain alkyl group is used. A light-emitting device with improved emission efficiency can be obtained with the use of a material having a five-membered ring skeleton in the host material.

Abstract: Provided is a novel organic compound, a benzofuropyrimidine derivative or a benzothienopyrimidine derivative, which is an organic compound represented by General Formula (G1) below. In General Formula (G1), Q represents oxygen or sulfur. Furthermore, A is a group having 12 to 100 carbon atoms in total and includes one or more of a benzene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, a triphenylene ring, a heteroaromatic ring including a dibenzothiophene ring, a heteroaromatic ring including a dibenzofuran ring, a heteroaromatic ring including a carbazole ring, a benzimidazole ring, and a triphenylamine structure.

Abstract: An object is to provide a light-emitting element which uses a plurality of kinds of light-emitting dopants and has high emission efficiency. In one embodiment of the present invention, a light-emitting device, a light-emitting module, a light-emitting display device, an electronic device, and a lighting device each having reduced power consumption by using the above light-emitting element are provided. Attention is paid to Förster mechanism, which is one of mechanisms of intermolecular energy transfer. Efficient energy transfer by Förster mechanism is achieved by making an emission wavelength of a molecule which donates energy overlap with a local maximum peak on the longest wavelength side of a graph obtained by multiplying an absorption spectrum of a molecule which receives energy by a wavelength raised to the fourth power.

Abstract: Provided is a novel light-emitting element, a light-emitting element with a long lifetime, or a light-emitting element with high emission efficiency. The light-emitting element includes an EL layer between a pair of electrodes. The EL layer includes at least a light-emitting layer containing a fluorescent substance and a host material, a first electron-transport layer containing a first electron-transport material, and a second electron-transport layer containing a second electron-transport material, which are in contact with each other and in this order. The LUMO level of each of the host material and the second electron-transport material is higher than the LUMO level of the first electron-transport material.

Abstract: An organic compound is represented by General Formula (G1). In the formula, each of R1 to R4 independently represents any of hydrogen (including deuterium), a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 6 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, and a substituent represented by General Formula (G1-1). Each of R5 to R8 independently represents any of hydrogen (including deuterium), a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 6 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, and a substituent represented by General Formula (G1-3). At least one of R5 to R8 represents a substituent represented by General Formula (G1-3).

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: A light-emitting element containing a light-emitting material with high luminous efficiency is provided. The light-emitting element includes a host material and a guest material. The host material includes a first organic compound and a second organic compound. In the first organic compound, a difference between a singlet excitation energy level and a triplet excitation energy level is larger than 0 eV and smaller than or equal to 0.2 eV. The HOMO level of one of the first organic compound and the second organic compound is higher than or equal to that of the other organic compound, and the LUMO level of the one of the organic compounds is higher than or equal to that of the other organic compound. The first organic compound and the second organic compound form an exciplex.

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: One object of this invention is to provide a novel light-emitting device with low power consumption. The light-emitting device includes a first light-emitting element and a second light-emitting element. The first light-emitting element includes a first electrode, a second electrode, and a light-emitting layer. The second light-emitting element includes the first electrode, a third electrode, and the light-emitting layer. The second electrode comprises only a first conductive film, and the third electrode comprises a second conductive film and a third conductive film. The first electrode has a function of reflecting light. The second conductive film has functions of reflecting light and transmitting light. The first conductive film and the third conductive film each have a function of transmitting light.

Abstract: A novel organometallic complex with high reliability is provided. A light-emitting element includes an EL layer between a pair of electrodes. The EL layer includes at least a light-emitting layer. The light-emitting layer contains an organometallic complex. The organometallic complex includes a first ligand and a second ligand which are coordinated to a central metal. The HOMO is distributed over the first ligand, and the LUMO is distributed over the second ligand. The first ligand and the second ligand are cyclometalated ligands.