A display device includes a substrate, a low refractive index layer disposed on the substrate, a first capping layer disposed on the low refractive index layer and directly contacting an upper surface of the low refractive index layer, a second capping layer disposed on the first capping layer, and a wavelength conversion layer disposed on the second capping layer and having a refractive index higher than a refractive index of the low refractive index layer, wherein a nitrogen atomic ratio of the first capping layer is different from a nitrogen atomic ratio of the second capping layer.