The display device includes: a substrate; a thin-film transistor disposed on the substrate; a passivation layer covering the thin-film transistor; a capping layer disposed on the passivation layer; and a pixel electrode disposed on the capping layer and connected to the thin-film transistor, wherein a thickness of the capping layer is determined according to: d1=(λ/2)×(1/2n), where d1 denotes the thickness of the capping layer, λ denotes a wavelength within visible wavelength range, and n denotes a ratio of refractive indices of the passivation layer to the capping layer.