Abstract: A light-emitting device with high heat resistance is provided. The light-emitting layer device includes an anode, a cathode; and an EL layer between the anode and the cathode. The EL layer includes a light-emitting layer and a first layer. The first layer is between the light-emitting layer and the cathode. The light-emitting layer is in contact with the first layer. The light-emitting layer includes a first organic compound and a light-emitting substance. The first layer includes a second organic compound. The light-emitting substance is a substance that emits blue light. The first organic compound is an organic compound including a fused aromatic hydrocarbon ring. The second organic compound is an organic compound including a heteroaromatic ring skeleton including one selected from a pyridine ring, a diazine ring, and a triazine ring; and a bicarbazole skeleton.

Abstract: A light-emitting device having favorable heat resistance is provided. The light-emitting device includes an anode, a cathode, and an EL layer positioned between the first anode and the cathode. The EL layer includes a light-emitting layer and a first layer. The first layer is positioned between the light-emitting layer and the cathode. The light-emitting layer and the first layer are in contact with each other. The light-emitting layer contains a first organic compound, a second organic compound, and a light-emitting substance. The first layer contains a third organic compound. The first organic compound and the third organic compound each have an electron-transport property. The second organic compound has a hole-transport property. The light-emitting substance emits red light. The first organic compound is represented by General Formula (G100). The third organic compound is represented by General Formula (G300).

Abstract: A light-emitting device with high resistance to heat in a fabrication process is provided. The light-emitting device includes an EL layer between an anode and a cathode. The EL layer includes at least a light-emitting layer and an electron-transport layer that includes a first electron-transport layer in contact with the light-emitting layer and a second electron-transport layer in contact with the first electron-transport layer. The first electron-transport layer includes a first heteroaromatic compound including at least one heteroaromatic ring. The second electron-transport layer includes a second heteroaromatic compound that includes at least one heteroaromatic ring and is different from the first heteroaromatic compound. The first heteroaromatic compound has a difference of 20° C. or less between the crystallization temperature (Tpc) of a powder state and the crystallization temperature (Ttc) of a thin film state. The second heteroaromatic compound has a difference of 100° C. or less between Tpc and Ttc.

Abstract: A novel mixed material for a light-emitting device with improved heat resistance is provided. The mixed material for a light-emitting device includes a first heteroaromatic compound and a second heteroaromatic compound. The first heteroaromatic compound includes a first heteroaromatic ring. The first heteroaromatic ring includes a ring including two or more nitrogen atoms and any one of a benzene ring and a pyridine ring or a ring including a diazine ring or a triazine ring. The second heteroaromatic compound includes a second heteroaromatic ring. The second heteroaromatic ring includes a ring including two or more nitrogen atoms and any one of a benzene ring and a pyridine ring or a ring including a diazine ring or a triazine ring. A structure of the first heteroaromatic ring is different from a structure of the second heteroaromatic ring.

Abstract: A novel mixed material with improved resistance is provided. The mixed material includes a first heteroaromatic compound and a second heteroaromatic compound, and the first heteroaromatic compound is represented by any one of General Formulae (G1) to (G6). The second heteroaromatic compound is not represented by the same general formula as that of the first heteroaromatic compound.

Abstract: A novel light-emitting device is provided. The light-emitting device includes a first electrode, a second electrode, and a light-emitting layer between the first electrode and the second electrode. The light-emitting layer includes an organometallic complex emitting phosphorescence at room temperature and a light-emitting material emitting fluorescence. The organometallic complex includes a ligand with at least one first substituent selected from a branched alkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms in a ring, and a trialkylsilyl group having 3 to 12 carbon atoms. An absorption spectrum of the light-emitting material has the longest-wavelength edge at a first wavelength ?abs (nm), and a phosphorescence spectrum of the organometallic complex has the shortest-wavelength edge at a second wavelength ?p (nm). The first wavelength ?abs (nm) is longer than the second wavelength ?p (nm).

Abstract: A novel organometallic complex is provided. One embodiment of the present invention provides a novel organometallic complex having a high quantum yield. An Ir complex has a structure including a 1H-naphtho[1,2-d]imidazole skeleton as a ligand and being represented by General Formula (G-1) below. Of Ns included in the 1H-naphtho[1,2-d]imidazole skeleton, N that is not bonded to Ir is bonded to a substituted or unsubstituted aryl group. In General Formula (G-1), each of R1 to R10 independently represents any of hydrogen, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, and an electron-withdrawing group, and Ar represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.