Light-emitting element, display device, electronic device, and lighting device

A light-emitting device comprising:

• a pair of electrodes;
• and
• a light-emitting layer between the pair of electrodes, the light-emitting layer comprising:
• a compound comprising a first molecule and a second molecule, the first molecule and the second molecule having the same molecular structure;
• and
• a phosphorescent compound as a guest material,
• wherein each of the first molecule and the second molecule comprises:
• a first skeleton comprising at least one of a π-electron rich heteroaromatic skeleton and an aromatic amine skeleton;
• and
• a second skeleton comprising a pyrimidine skeleton or a triazine skeleton,
• wherein the first molecule and the second molecule are configured to form an excited complex with the first skeleton in the first molecule and the second skeleton in the second molecule, and
• wherein a difference between a peak of an emission spectrum of the compound in a toluene solution and a peak of an emission spectrum of a thin film of the compound is 30 nm or more.

A light-emitting device comprising:

• a pair of electrodes;
• a first light-emitting layer and a second light-emitting layer between the pair of electrodes;
• and
• a charge-generation layer between the first light-emitting layer and the second light-emitting layer,
• wherein the first light-emitting layer comprises:
• a compound comprising a first molecule and a second molecule, the first molecule and the second molecule having the same molecular structure;
• and
• a phosphorescent compound as a guest material,
• wherein each of the first molecule and the second molecule comprises:
• a first skeleton comprising at least one of a π-electron rich heteroaromatic skeleton and an aromatic amine skeleton;
• and
• a second skeleton comprising a π-electron deficient heteroaromatic skeleton,
• wherein the first molecule and the second molecule are configured to form an excited complex with the first skeleton in the first molecule and the second skeleton in the second molecule, and
• wherein a difference between a peak of an emission spectrum of the compound in a toluene solution and a peak of an emission spectrum of a thin film of the compound is 30 nm or more.