a blue sub-pixel comprising a plurality of first light emitting units in a number of N1;

a green sub-pixel comprising a plurality of second light emitting units in a number of N2; and

a red sub-pixel comprising a plurality of third light emitting units in a number of N3,

wherein an area of the green sub-pixel is greater than an area of the red sub-pixel, the area of the red sub-pixel is greater than an area of the blue sub-pixel, the first light emitting units, the second light emitting units and the third light emitting units all emit lights in a color of blue, and a green wavelength conversion layer and a red wavelength conversion layer are so arranged that the blue light from the second light emitting units and the blue light from the third light emitting units go through the green wavelength conversion layer and the red wavelength conversion layer respectively, wherein N1 is greater than or equal to 6, N1<N2 and N1<N3, wherein N2/N1 is between 2.1 and 3.68, and N3/N1 is between 1.52 and 2.53, and

wherein a conversion efficiency of the green wavelength conversion layer is in a range from 20% to 35%, and a conversion efficiency of the red wavelength conversion layer is in a range from 24% to 40%;

wherein the plurality of first light emitting units are irregularly spaced in the area of the blue sub-pixel, the plurality of second light emitting units are irregularly spaced in the area of the green sub-pixel, and the plurality of third light emitting units are irregularly spaced in the area of the red sub-pixel.