Advances in solid state lighting (SSL) - lighting that uses light-emitting diodes (LEDs) - promises to fundamentally alter lighting in the future.
LED stands for Light Emitting Diode. A diode is a semiconductor that only allows passage of electrical current in one direction.
An LED consists of two elements of processed material: P-type semiconductors and N-type semiconductors. These two elements are placed in direct contact, forming a region called the P-N junction. The main difference between an LED and other diodes is that an LED is specifically designed to produce photons and has a transparent package that allows visible energy (light) to pass through.
Originally only used for low-light indicator type applications, LED technology has evolved in many areas. Newer color development (blue and white in particular) and Higher Brightness LEDs have made these devices more popular for many applications.
What types of LEDs are there?
Low power LEDs commonly come in 5 mm size, although they are also available in 3 mm and 8 mm sizes. These are fractional wattage devices, typically 0.1 watt, operate at low current (~20 milliamps) and low voltage (3.2 volts DC), and produce a small amount of light, perhaps 2 to 4 lumens.
High power LEDs come in 1-3 watt packages. They are driven at much higher current, typically 350, 700, or 1000 mA, and – with current technology – can produce 40-80 lumens per 1-watt package.
Future of LED Technology
• Replacements for incandescent lamps and PAR 38 halogen lamps
• See DOE’s LPrize competition on how manufacturers are racing to produce a replacement for the most-used fixture
• Applications for Industrial, Food-Processing, and Lab environments are growing everyday