How Do LED Light Bulbs Work?
An LED is capable of generating light because of the arrangement of the two semiconductor materials located between its electrodes:
N-type: A semiconductor with extra electrons (also known as extra negatively charged particles).
P-type: A semiconductor with extra holes (also known as extra positively charged particles).
Connecting the N-type semiconductor to the negative electrode and the P-type semiconductor to the positive electrode activates the electrons so they can flow across the junction from the negative to the positive layer. As the extra electrons (negatively charged particles) move through the extra holes (positively charged particles), they emit light.
The conductive material that makes up LEDs is typically aluminum-gallium-arsenide, but there are other kinds. The materials are selected specifically because they produce photons that will be released on the visible portion of the light spectrum. The type of material chosen and the amount used alters the colour of the light because each material generates photons at different wavelengths, affecting how it appears to the human eye.
Diodes use InGaN as the common semiconductor because it creates a bright blue light and, like fluorescents, a phosphor coated casing can be used to create white light. In an LED light bulb , a series of diodes is wired together in an array, surrounded by a reflector and possibly another plastic or glass casing in the shape of the bulb you need. Since the casing of each diode refracts the light in a certain direction, LEDs are very good at directional lighting. A household omnidirectional LED is more like a traditional light bulb. The diodes are set in a cylinder formation, covering nearly 360 degrees horizontally. Diodes are also placed on the top of the cylindrical array to provide upward lighting. This formation allows the light to mimic the beam spread of incandescent bulbs.