A display device having high light-extraction efficiency is provided. A low-power display device is provided. In a red or green pixel included in the display device, a light-emitting element, an optically functional layer, and a wavelength-conversion layer are stacked in this order. The light-emitting element emits blue light, the optically functional layer transmits the blue light and reflects red and green light, and the wavelength-conversion layer converts the blue light into red or green light. The blue light emitted by the light-emitting element passes through the optically functional layer and enters the wavelength-conversion layer, and red or green light is emitted to the outside. The red or green light emitted from the wavelength-conversion layer to the optically functional layer side is reflected by the optically functional layer and emitted to the outside, which improves light-extraction efficiency.