Abstract: An object is to provide a novel organometallic complex. Another object is to provide an organometallic complex that can exhibit yellow to blue phosphorescence. A platinum complex with a tetracoordinate ligand including a phenothiazine skeleton or a phenoxazine skeleton is provided. In the ligand, nitrogen at the 10-position and carbon at the 2-position of the phenothiazine skeleton or the phenoxazine skeleton have a pyridyl group and a phenoxy group, respectively. A five-membered heteroaromatic residue is present at the 3-position of the phenoxy group. The five-membered heteroaromatic residue has two or three nitrogen atoms in its skeleton. Carbon at the 1-position of the phenothiazine skeleton or the phenoxazine skeleton and carbon at the 2-position of the phenoxy group are bonded to platinum, and nitrogen of the pyridyl group and nitrogen or carbene carbon of the five-membered heteroaromatic residue are coordinated to platinum.

Abstract: Provided is 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 that of the second organic compound, and the HOMO level of the first organic compound is lower than that of the second organic compound. The LUMO level of a guest material is higher than that of the first organic compound, and the HOMO level of the guest material is lower than that 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: 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 compound includes a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton, a first substituent, and a second substituent. Each of the first substituent and the second substituent includes a furan skeleton, a thiophene skeleton, or a pyrrole skeleton. The first substituent is bonded to a pyrimidine ring included in the benzofuropyrimidine skeleton or a pyrimidine ring included in the benzothienopyrimidine skeleton. The second substituent is bonded to a benzene ring included in the benzofuropyrimidine skeleton or a benzene ring included in the benzothienopyrimidine skeleton. The light-emitting element includes the compound.

Abstract: Provided is a novel heterocyclic compound, a novel heterocyclic compound that can be used in a light-emitting element, or a highly reliable light-emitting device, electronic device, and lighting device in each of which the light-emitting element using the novel heterocyclic compound is used. One embodiment of the present invention is a heterocyclic compound represented by General Formula (G1). In General Formula (G1), each of A1 and A2 independently represents nitrogen or carbon bonded to hydrogen, and at least one of A1 and A2 represents nitrogen; Ar represents a substituted or unsubstituted arylene group having 6 to 18 carbon atoms; B represents a substituted or unsubstituted fluorenyl group; and R1 represents hydrogen, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 13 carbon atoms.

Abstract: Light-emitting elements having high emission efficiency and long lifetime can be provided. By forming light-emitting devices including the light-emitting elements, the light-emitting devices having low power consumption and long lifetime can be provided. A light-emitting device comprises a light-emitting element including a light-emitting layer between a first electrode and a second electrode. The light-emitting layer includes a first organic compound having a hole-transporting property, a second organic compound having an electron transporting property, and an organometallic complex. A central metal of the organometallic complex is an element belonging to one of Group 9 and Group 10, and a ligand of the organometallic complex is a ligand having a pyrazine skeleton.

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 with a light-emitting substance comprising an organometallic complex. The organometallic complex having a structure represented by General Formula (G0). In the formula, 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 and R2 each represent an alkyl group having 1 to 6 carbon atoms.

Abstract: A light-emitting element having high external quantum efficiency is provided. A light-emitting element having a long lifetime is provided. A light-emitting element is provided which includes a light-emitting layer containing a phosphorescent compound, a first organic compound, and a second organic compound between a pair of electrodes, in which a combination of the first organic compound and the second organic compound forms an exciplex (excited complex). The light-emitting element transfers energy by utilizing an overlap between the emission spectrum of the exciplex and the absorption spectrum of the phosphorescent compound and thus has high energy transfer efficiency. Therefore, a light-emitting element having high external quantum efficiency can be obtained.

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: A light-emitting element having high external quantum efficiency is provided. A light-emitting element having a long lifetime is provided. A light-emitting element is provided which includes a light-emitting layer containing a phosphorescent compound, a first organic compound, and a second organic compound between a pair of electrodes, in which a combination of the first organic compound and the second organic compound forms an exciplex (excited complex). The light-emitting element transfers energy by utilizing an overlap between the emission spectrum of the exciplex and the absorption spectrum of the phosphorescent compound and thus has high energy transfer efficiency. Therefore, a light-emitting element having high external quantum efficiency can be obtained.

Abstract: A light-emitting element having high external quantum efficiency is provided. A light-emitting element having a long lifetime is provided. A light-emitting element is provided which includes a light-emitting layer containing a phosphorescent compound, a first organic compound, and a second organic compound between a pair of electrodes, in which a combination of the first organic compound and the second organic compound forms an exciplex (excited complex). The light-emitting element transfers energy by utilizing an overlap between the emission spectrum of the exciplex and the absorption spectrum of the phosphorescent compound and thus has high energy transfer efficiency. Therefore, a light-emitting element having high external quantum efficiency can be obtained.

Abstract: A compound includes a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton, a first substituent, and a second substituent. Each of the first substituent and the second substituent includes a furan skeleton, a thiophene skeleton, or a pyrrole skeleton. The first substituent is bonded to a pyrimidine ring included in the benzofuropyrimidine skeleton or a pyrimidine ring included in the benzothienopyrimidine skeleton. The second substituent is bonded to a benzene ring included in the benzofuropyrimidine skeleton or a benzene ring included in the benzothienopyrimidine skeleton. The light-emitting element includes the compound.

Abstract: A light-emitting element having high external quantum efficiency is provided. A light-emitting element having a long lifetime is provided. A light-emitting element is provided which includes a light-emitting layer containing a phosphorescent compound, a first organic compound, and a second organic compound between a pair of electrodes, in which a combination of the first organic compound and the second organic compound forms an exciplex (excited complex). The light-emitting element transfers energy by utilizing an overlap between the emission spectrum of the exciplex and the absorption spectrum of the phosphorescent compound and thus has high energy transfer efficiency. Therefore, a light-emitting element having high external quantum efficiency can be obtained.

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 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: To provide a novel organometallic complex. The organometallic complex is represented by General Formula (G1) and includes a central metal, a first ligand, and a second ligand. The first ligand and the second ligand are cyclometalated ligands. At least one of the first ligand and the second ligand includes a substituted or unsubstituted. aryl. group as a substituent. In General Formula (G1), each of R1 to R15 independently represents any of hydrogen, a halogen group, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 13 carbon atoms, and a substituted or unsubstituted heteroaryl group having 3 to 12 carbon atoms. Note that at least one of R1 to R15 represents a substituted or unsubstituted aryl group having 6 to 13 carbon atoms.

Abstract: A novel organic compound that can be used as an electron-injection material or an electron-transport material of a light-emitting element is provided. An organic compound with which a display device having less crosstalk can be obtained is provided. A light-emitting device, a display device, and an electronic device each having less crosstalk are provided. An organic compound including two or three benzo[h]quinazoline rings is provided. In the organic compound, two or three benzo[h]quinazoline rings are preferably included in the substituent including an aromatic ring or a heteroaromatic ring and having 3 to 30 carbon atoms. When two or three benzo[h]quinazoline rings are included in a substituent particularly including a heteroaromatic ring and having 3 to 30 carbon atoms, a high electron-transport property can be obtained.

Abstract: A novel heterocyclic compound is provided. A novel heterocyclic compound that can be used for a light-emitting element is provided. A novel heterocyclic compound that can improve the reliability of a light-emitting element when used for a light-emitting element is provided. A light-emitting element, a light-emitting device, an electronic appliance, or a lighting device which includes the novel heterocyclic compound and is highly reliable is provided. One embodiment of the present invention is a heterocyclic compound represented by a general formula (G0). In the general formula (G0), A represents a dibenzo[f,h]quinoxalinyl group, B represents a substituted or unsubstituted fluorenyl group, and Ar represents a substituted or unsubstituted arylene group having 6 to 25 carbon atoms.

Abstract: An organometallic iridium complex that has high emission efficiency and a long lifetime and emits deep red light (emission wavelength: around 700 nm) is provided. The organometallic iridium complex has a ligand that is represented by General Formula (G0) and has at least a dimethyl phenyl group and a quinoxaline skeleton. In the formula, R1 to R3 separately represent an alkyl group having 1 to 6 carbon atoms, a phenyl group, or a phenyl group having an alkyl group having 1 to 6 carbon atoms as a substituent.