A light-emitting diode is provided. The light-emitting diode includes a multiple quantum well structure to generate a light beam with a broadband blue spectrum. The light beam contains a first sub-light beam with a first wavelength and a second sub-light beam with a second wavelength. A difference between the first wavelength and the second wavelength ranges from 1 nm to 50 nm, and the light-emitting diode has a Wall-Plug-Efficiency (WPE) of greater than 0.45 under an operating current density of 120 mA/mm2.