Abstract: Provided as a novel substance is a long-lifetime organometallic iridium complex emitting yellow light with high emission efficiency. The organometallic iridium complex is represented by General Formula (G1) and has a structure in which a phenyl group whose 2-position and 6-position are each substituted by an alkyl group is bonded to the 4-position of pyrimidine. In General Formula (G1), R1 and R2 each independently represent a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms.

Abstract: An organometallic complex emitting blue phosphorescence which can be manufactured inexpensively is provided. An organometallic complex in which nitrogen at the 1-position of a 5-aryl-4H-1,2,4-triazole derivative is coordinated to a Group 9 metal or a Group 10 metal, the aryl group is bonded to the Group 9 metal or the Group 10 metal, and the 5-aryl-4H-1,2,4-triazole derivative is a 3-aryl-5,6,7,8-tetrahydro-4H-[1,2,4]triazolo[4,3-a]pyridine derivative is provided. The organometallic complex emits green to blue phosphorescence and has a cost advantage.

Abstract: A light-emitting element having extremely high efficiency of approximately 25% is provided. The light-emitting element includes a light-emitting layer which contains a phosphorescent guest, an n-type host, and a p-type host, where the light-emitting layer is interposed between an n-type layer including the n-type host and a p-type layer including the p-type host, and where the n-type host and the p-type host are able to form an exciplex in the light-emitting layer. The light-emitting element exhibits an extremely high emission efficiency (power efficiency of 74.3 lm/W, external quantum efficiency of 24.5%, energy efficiency of 19.3%) at a low driving voltage (2.6 V) at which luminance of 1200 cd/m2 is attainable.

Abstract: A light-emitting element having high external quantum efficiency is provided. A light-emitting element having low drive voltage is provided. Provided is a light-emitting element which includes a light-emitting layer containing a phosphorescent compound, a first organic compound, and a second organic compound between a pair of electrodes. A combination of the first organic compound and the second organic compound forms an exciplex (excited complex). An emission spectrum of the exciplex overlaps with an absorption band located on the longest wavelength side of an absorption spectrum of the phosphorescent compound. A peak wavelength of the emission spectrum of the exciplex is longer than or equal to a peak wavelength of the absorption band located on the longest wavelength side of the absorption spectrum of the phosphorescent compound.

Abstract: As a novel substance having a novel skeleton, a novel organometallic complex that can emit phosphorescence in the green to red wavelength region and has high emission efficiency and a high yield of synthesis is provided. One embodiment of the present invention is an organometallic complex in which a diketone having a five-membered or six-membered alicyclic structure composed of carbon and hydrogen is a ligand. In the formula, L represents a bidentate aromatic ligand and has at least a bond between carbon of an aromatic ring in the aromatic ligand and Ir. X represents a five-membered or six-membered alicycle composed of carbon and hydrogen. Further, R1 represents a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms.

Abstract: The light emitting element includes a first electrode and a second electrode, between which a light emitting layer, a hole transporting layer provide in contact with the light emitting layer, an electron transporting layer provided in contact with the light emitting layer, and a mixed layer provided between the electron transporting layer and the second electrode. The mixed layer includes an electron transporting substance and a substance showing an electron donating property with respect to the electron transporting substance. The light emitting layer includes an organometallic complex represented in General Formula (1) and a host. R1 and R2 each represent an electron-withdrawing substituent group. R3 and R4 each represent any of hydrogen or an alkyl group having 1 to 4 carbon atoms. L represents any of a monoanionic ligand having a beta-diketone structure, a monoanionic bidentate chelating ligand having a carboxyl group, or a monoanionic bidentate chelating ligand having a phenolic hydroxyl group.

Abstract: An object is to provide a novel organometallic complex capable of emitting phosphorescence, an organometallic complex which exhibits deep red emission, and a light-emitting element which provides deep red emission. Provided is an organometallic complex having a structure represented by the following General Formula (G1). In the formula, R1, R2, R3, R4, R5, R6, R7, R8, and R9 represent substituents, and M is a central metal and represents either a Group 9 element or a Group 10 element.

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: An object is to provide a novel organometallic complex. Another object is to provide an organometallic complex exhibiting green to blue phosphorescence. Another object is to provide an organometallic complex having deep HOMO and exhibiting green to blue phosphorescence. Another object is to provide a light-emitting element with high emission efficiency. Another object is to provide a light-emitting element exhibiting green to blue phosphorescence and having low drive voltage. To provide an organometallic complex which includes a 1,2,4-triazole skeleton and in which an N-carbazolyl group is bonded to the 3-position of the 1,2,4-triazole skeleton via a phenylene group, a phenyl group is bonded to the 4-position of the 1,2,4-triazole skeleton, the 2-position of the 1,2,4-triazole skeleton coordinates to iridium, and the phenylene group is bonded to the iridium. To provide a light-emitting element including the organometallic complex as an emission center.

Abstract: A light-emitting element with high emission efficiency is provided. In addition, a light-emitting element having a low driving voltage is provided. Furthermore, a novel compound which can be used for a transport layer, a host material, or a light-emitting material of a light-emitting element is provided. A novel compound including a benzothienopyrimidine skeleton is provided. Furthermore, a light-emitting element including a pair of electrodes and an EL layer sandwiched between the pair of electrodes is provided. The EL layer contains a substance including the benzothienopyrimidine skeleton.

Abstract: Provided is a 5,6-diaryl-2-pyrazyl triflate, its synthetic method, and a method for synthesizing an organometallic complex having a triarylpyrazine ligand from the 5,6-diaryl-2-pyrazyl triflate. The triflate is readily obtained from the corresponding 5,6-diarylpyrazin-2-ol, and the palladium-catalyzed coupling of the 5,6-diaryl-2-pyrazyl triflate with an arylboronic acid derivative leads to a high yield of a triarylpyrazine derivative having high purity. The use of the triarylpyrazine derivative in the reaction with a metal compound such as a metal chloride results in an ortho-metallated organometallic complex with high purity. The high purity of the organometallic complex contributes to the extremely high durability of a light-emitting element.

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: An organometallic complex according to the present invention comprises a structure represented by the following general formula (1). In the formula, R1 to R5 are any one selected from the group consisting of hydrogen, a halogen element, an acyl group, an alkyl group, an alkoxy group, an aryl group, a cyano group, and a heterocyclic group, Ar is an aryl group having an electron-withdrawing group or a heterocyclic group having electron-drawing group, and M is an element of Group 9 or an element of Group 10.

Abstract: To provide a long-lifetime organometallic iridium complex exhibiting yellow light emission with high emission efficiency as a novel substance. The organometallic iridium complex includes a ligand in which an unsubstituted phenyl group is bonded to each of the 2-position and the 5-position of pyrimidine. The organometallic iridium complex has a structure represented by General Formula (G1).

Abstract: An organic light-emitting element having high efficiency and long lifetime is provided. An organic light-emitting body is provided which includes a host having a high electron-transport property (n-type host), a host having a high hole-transport property (p-type host), and a guest such as an iridium complex and in which the n-type host and the p-type host are located so as to be adjacent to each other. When an electron and a hole are injected to such a light-emitting body, the electron is trapped by the n-type host and the hole is trapped by the p-type host. Then, both the electron and the hole are injected to the guest, and thus the guest is brought into an excited state. In this process, less thermal deactivation occurs and the working rate of the guest is high; thus, highly efficient light emission can be obtained.

Abstract: Disclosed is a phosphorescent organometallic complex having: a 6-membered aromatic heterocycle having a nitrogen atom; iridium or platinum to which the nitrogen atom coordinates; and an aryl group which is bonded to an ?-carbon of the nitrogen atom and is ortho-metalated with the iridium or platinum, where at least one of the aromatic heterocycle and the aryl group has an alicyclic hydrocarbon having an intramolecular carbon-carbon bridged bond as a substituent. The ability of the bulky structure of the alicyclic hydrocarbon to inhibit aggregation of the organometallic complex, concerted with the strong electron-donating property of the alicyclic hydrocarbon to the aromatic heterocycle or the aryl group, contributes to the increase in absorption coefficient and phosphorescent efficiency of the organometallic complex. The improved absorption coefficient and the phosphorescent efficiency allow the formation of a light-emitting element with excellent external quantum efficiency over 25%.

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: Provided is a light-emitting element with high external quantum efficiency, or a light-emitting element with a long lifetime. The light-emitting element includes, between a pair of electrodes, a light-emitting layer including a guest material and a host material, in which an emission spectrum of the host material overlaps with an absorption spectrum of the guest material, and phosphorescence is emitted by conversion of an excitation energy of the host material into an excitation energy of the guest material. By using the overlap between the emission spectrum of the host material and the absorption spectrum of the guest material, the energy smoothly transfers from the host material to the guest material, so that the energy transfer efficiency of the light-emitting element is high. Accordingly, a light-emitting element with high external quantum efficiency can be achieved.

Abstract: A novel method includes a synthetic pathway in which ?-diketone and a 1-(haloaryl)ethane-1,2-diamine derivative are cyclized to each other to form a 2-(haloaryl)pyrazine derivative. Further, a 2-arylpyrazine derivative having an aryl group or a heteroaryl group as a substituent is synthesized by coupling the 2-(haloaryl)pyrazine derivative obtained by the above synthetic pathway and an arylboronic acid or a heteroarylboronic acid. The 2-arylpyrazine derivative obtained by the novel method is useful for a light-emitting element, a light-emitting device, an electronic device, or a lighting device with high emission efficiency.

Abstract: An organometallic complex having a structure represented by the general formula (G1) is synthesized and applied to a light-emitting element. In the formula, R3 represents either an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkoxycarbonyl group having 1 to 5 carbon atoms; R2 and R3 each show either hydrogen or an alkyl group 1 to 4 carbon atoms; Ar represents an arylene group having 6 to 25 carbon atoms; M is a center metal selected from Group 9 element and Group 10 element.