Abstract: A triarylamine derivative represented by a general formula (G1) given below is provided. Note that in the formula, Ar represents either a substituted or unsubstituted phenyl group or a substituted or unsubstituted biphenyl group; ? represents a substituted or unsubstituted naphthyl group; ? represents either hydrogen or a substituted or unsubstituted naphthyl group; n and m each independently represent 1 or 2; and R1 to R8 each independently represent any of hydrogen, an alkyl group having 1 to 6 carbon atoms, or a phenyl group.

Abstract: A technique of manufacturing a display device with high productivity is provided. In addition, a high-definition display device with high color purity is provided. By adjusting the optical path length between an electrode having a reflective property and a light-emitting layer by the central wavelength of a wavelength range of light passing through a color filter layer, the high-definition display device with high color purity is provided without performing selective deposition of light-emitting layers. In a light-emitting element, a plurality of light-emitting layers emitting light of different colors are stacked. The closer the light-emitting layer is positioned to the electrode having a reflective property, the shorter the wavelength of light emitted from the light-emitting layer is.

Abstract: An organometallic complex which can be provided at low cost and which emits blue phosphorescence 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 is also advantageous in terms of cost.

Abstract: A layer including an organic compound at least includes a layer serving as a light-emitting layer in which a first layer, a second layer, a third layer, and a fourth layer are stacked in that order over an anode. The first layer includes a first light-emitting substance, the second layer includes a second light-emitting substance, the third layer includes a third light-emitting substance, and the fourth layer includes a fourth light-emitting substance. Emission peak wavelengths of the first light-emitting substance and the fourth light-emitting substance are shorter than an emission peak wavelength of the third light-emitting substance, and the emission peak wavelength of the third light-emitting substance is shorter than an emission peak wavelength of the second light-emitting substance. Each of the first layer, the second layer, and the third layer has a hole-transporting property, and the fourth layer has an electron-transporting property.