LEDs are semiconductor components that convert electrical energy directly into light energy. In 1962, General Electric's Holonyak invented the red LED. After 54 years of development, the red, orange, green, blue, and purple color LED lights have all been industrialized and commercialized, and artificial can already create a colorful new vision. At the 15th National LED Industry Development and Technology Seminar held recently and the 2016 National LED Display Application Technology Exchange and Industry Development Seminar, Jiang Fengyi, Vice President of Nanchang University, proposed that the era of multi-primary LED synthetic lighting industry is coming. Jiang Fengyi said that as Holonyak said four years ago, LED is still in its infancy. The existing LED lighting technology solution is realized by the method of blue light + phosphor, the light effect and quality are difficult to coordinate, the lumen efficiency is high, has reached 150lm/W, but the blue light ratio is too large, the blue light is missing, the red light insufficient. Jiang Fengyi believes that LED lighting technology still has a lot of room for development. The new generation of LED lighting technology will use a multi-primary LED synthesis solution that directly synthesizes white light with red, yellow, green, cyan, and blue light without the need for phosphors. Specifically, when the luminous efficacy of blue, cyan, green, yellow, and red light reaches 70%, 55%, 45%, 25%, and 55%, respectively, the color rendering index is 97.8, the color temperature is 3000K, and the luminous efficiency is 136 lm. /W's satisfactory results. From the data of 2015, the power efficiencies of visible light LEDs are: blue light 65%, green light 35%, yellow light 10%, red light 52%. It can be seen that the difficulty in the synthesis of multi-primary LEDs is mainly due to the improvement of the efficiency of yellow light, and the problem of the yellow light gap is that the yellow light effects of AlGaInN and AlGaInP are very low. In recent years, domestic and foreign scientific research forces have been actively exploring how to improve the light efficiency of Huangguang. Nanchang University has also started to develop yellow LED growth technology with self-made MOCVD equipment since 2015. According to Jiang Fengyi, Nanchang University's silicon substrate LED technology won the first prize of the 2015 National Technology Invention Award, which is the third blue LED technology route in addition to US silicon carbide technology and Japanese sapphire technology. Using this technical route, Nanchang University controls the V-pit structure through epitaxial process, and the disadvantage of high dislocation density becomes an advantage, and good device performance is obtained. In fact, if the silicon substrate LED is fabricated into a conventional structure, the LED light-emitting efficiency is low due to the absorption of the silicon substrate and the blocking of the electrodes. However, through the substrate transfer technology and the complementary electrode structure, no current is passed directly under the N electrode to force the region to emit light, which solves the problem of the light blocking of the electrode; a mirror is designed to solve the problem of substrate light absorption. At the same time, the silicon substrate LED is single-sided, and the light is easier to control. Jiang Fengyi said that after a series of efforts, Nanchang University has achieved a luminous efficiency of 22.7% of yellow LEDs. In the next five years, we will continue to strive to achieve the 25% target. With the significant mitigation of the Huangguang Divide, the multi-primary LED synthetic lighting industry is approaching, and will have good development prospects in high-quality lighting, intelligent lighting and visible light communication.
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