- Seoul Semiconductor manufacturers and packages a wide selection of light emitting diodes (LEDs) for the automotive, lighting, appliance, mobile, signage, and back lighting units (BLU) markets. The company is the world’s fifth largest LED supplier, holding more than 10, 000 patents globally, while offering a wide range of LED technology and production capacity in areas such as "nPola", deep UV LEDs, and "Acrich", the world’s first commercially produced AC LED.