Light-emitting diode emitted, so the attainment of high efficiency in blue LEDs was quickly followed by the development of the first white LED. In this device a :Ce (known as "YAG") cerium doped phosphor coating on the emitter absorbs some of the blue emission and produces yellow light through fluorescence. The combination of that yellow with remaining blue light appears white to the eye. However, using different phosphors (fluorescent materials) it also became possible to instead produce green and red light through fluorescence. The resulting mixture of red, green and blue is not only perceived by humans as white light but is
LED filament LED filament An LED filament light bulb is an LED lamp which is designed to resemble a traditional incandescent light bulb with visible filaments, for aesthetic and light distribution purposes. It produces its light by LED filaments, multi-diode structures that resemble the filament of an incandescent light bulb. They are designed as drop-in replacements for conventional clear incandescent bulbs used in decorative light fixtures, such as table lamps, pendant lights, chandeliers, and bulb-based candelabras. They have the appearance of traditional incandescent bulbs but the higher efficiency of light emitting diodes (LEDs). A LED filament type design light bulb was produced