1. A display device comprising:a cover window comprising a curved portion and a flat portion; and
a display panel comprising:
a light-emitting unit on the substrate and comprising an organic light emitting device; and
a thin film on the light-emitting unit, the thin film comprising an organic layer and an inorganic layer,
wherein the display panel is smaller in at least one of length or width than the cover window, and defines:
a first display panel portion on the flat portion of the cover window; and
a second display panel portion extending in a curved shape from the first display panel portion and on the curved portion of the cover window, and
wherein the cover window is a single piece.