Disclosed is a light-emitting device. The light-emitting device comprises a blue light-emitting source and a light-emitting source. The light-emitting source includes first semiconductor nanocrystals and second semiconductor nanocrystals. The first and second nanocrystals emit lights of different wavelengths from each other to produce a color complementary to blue. The first and second semiconductor nanocrystals are spatially clustered to form first and second composites respectively.