ABSTRACT
Light-emitting diodes (LEDs) are not new topics. The development history of LEDs has experienced more than 100 years since Henry Joseph Round published the first report on electroluminescence in 1907. Mixing red/green/blue LED chips with an electronic circuit that can adjust the relative power ratio of the three LEDs can flexibly generate different color light, and in principle, it can generate the most efficient white light due to the lack of use of the wavelength-convert material. The white light generated by the quantum dot (QD) excitation is a new way, which is put forward in recent years. QDs have many advantages, for instance, wide absorption spectrum, narrow emission spectrum, long fluorescent life, high-photoluminescence quantum yields, low scattering and good color saturation. Luminous efficacy is the ratio of the luminous flux emitted by the LED to the electric power consumption. Color temperature is an important index of white LED color parameters.
