A display device including pixels respectively containing a plurality of subpixels, the display device comprises: a light emitting diode (LED) array including a plurality of LED cells, the plurality of LED cells provided in the plurality of subpixels, the plurality of LED cells configured to emit light having substantially the same wavelength, each of the plurality of LED cells having a first surface and a second surface; thin-film transistor (TFT) circuitry including a plurality of TFT cells, each of the plurality of TFT cells disposed on the first surface of an LED cell of the plurality of LED cells and including source and drain regions and a gate electrode disposed between the source and drain regions; a wavelength conversion pattern disposed on the second surface of an LED cell of the plurality of LED cells, the wavelength conversion pattern including a composite of a quantum dot and/or a polymer, the quantum dot configured to emit different colors of light from colors of light emitted from other quantum dots of other wavelength conversion patterns; and a light blocking wall disposed between two of the plurality of subpixels including the plurality of LED cells and between wavelength conversion patterns to separate the plurality of subpixels.