. . "The light-emitting layer contains host materials and guest materials which have a common skeleton represented by general formulas (1), (9), and (14). wherein R1 is a hydrogen atom, a lower alkyl group, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent, R2 to R5, each of which may be the same or different, are individually a hydrogen atom, a halogen at" . . .