Lighting devices are one such technology, in which most of the energy is wasted during the production of light. Lighting alone consumes more than 20% of total energy demand. Hence, a new lighting technology, known as a light-emitting diode (LED), evolved to reduce the energy demand. Red-emitting LEDs opened up the possibility of creating the entire visible spectrum through multiple combinations of blue-, green-, and red-emitting LEDs. The fascinating thing about LEDs is that the light can be produced by tiny semiconductor devices, which further helped in miniaturizing lighting technology. Gallium phosphide is an indirect—band gap semiconductor substrate that emits light in the green color wavelength. Types of Light-Emitting Diode. LEDs can be broadly classified into two main categories: Visible LEDs and Invisible LEDs. Red-emitting phosphors with narrowband emission spectra play an essential role in the manufacture of high-quality LEDs. Blue phosphor is a promising candidates for the development of white light—emitting diodes (WLEDs).