Basic principles of LED chip luminescence

Its working principle is to use the material of the light-emitting diode: that is, the compound of group III-V elements, to form a semiconductor with a PN junction surface on a single crystal. When the electrons and holes are combined to reach thermal equilibrium by applying a Vcc voltage externally, the excess energy will be released directly in the form of light. Instead of using a filter to indirectly obtain the required spectrum like a traditional light bulb.

As for the luminous efficiency and luminous wavelength, they are related to the materials, structure, and additives used. (The schematic diagram shows the basic luminous principle)

Once the current of the light-emitting diode flows from the P side to the N side, holes are injected into the P side electrode, and electrons are injected into the N side electrode. The holes move (diffusion) in the P layer, and the electrons move (diffusion) in the N layer, reaching the PN junction. If the energy of the holes and electrons reaches a certain value (Diffusion voltage, Vd) or above, the holes will cross the PN junction into the N layer, and recombine with a large number of electrons to emit light. The electrons will also cross the PN junction into the P layer, and recombine with a large number of holes to emit light.