Oval LED Wholesale Prices, Manufacturers, Sales, Hotline 【Nanjing Wesbo Electronics Co., Ltd.】 Light Emitting Diodes (LEDs) are composed of a PN junction like regular diodes and have unidirectional conductivity. When a forward voltage is applied to the LED, the holes injected from the P region to the N region and the electrons injected from the N region to the P region recombine within a few micrometers near the PN junction, emitting spontaneous fluorescence. The energy states of electrons and holes in different semiconductor materials are different. The amount of energy released upon recombination varies, with more energy release resulting in shorter light wavelengths. Commonly used LEDs emit red, green, or yellow light. The reverse breakdown voltage of an LED is greater than 5 volts. Its forward voltage-current characteristic curve is very steep, and a current-limiting resistor must be connected in series during use to control the current through the diode.