Let’s make light on the LED Phenomenon

Light Emitting Diodes (LEDs) probably marked the most revolutionary progress since men started using electricity to make light.

LEDs are semiconductor diodes, electronic devices that permit current to flow in only one direction. An extremely pure semiconductor is doped with different elements in order to modify its electric properties, creating an excess of positive or negative charges (p-doped and n-doped). The diode is formed by bringing these two slightly different versions together to form a PN junction. In a PN junction, the P side contains excess positive charge while the N side contains excess negative charge.

When a voltage is applied to the PN junction, electrons move from the N area toward the P area. The electron energy is converted to light as electrons flow though the junction. This converted electron energy depends on the different kind of doped semiconductor and defines the wavelength of the resulting coloured light.

LEDs for lighting were first developed in the 1960s, but at the beginning only for indication applications, (light source as something to be seen), taking advantage of the main characteristics.

The first LEDs were red, and immediately used for signalling application. In the 1970s the visible spectrum continued to become more complete with green, yellow and orange LEDs, and new applications continued to grow especially with LED displays for calculators, digital watches and test equipment.

The 1980s saw the development of new LED technologies, based on a new kind of material used for diode construction, that,  as a result, created a more efficient generation of LEDs with less power consumption and up to ten times the brightness level.  This increased brightness also made them useful for outdoor signs.

In the 1990s development continued even faster and new types of High-Brightness LEDs (HB-LEDs) started to be produced, massively used for traffic lights and other applications never covered before. A few years later Nichia, one of the most important companies in LED development, created the high brightness blue LED. This was a key step in LED technology, because by coating this blue HB-LED with phosphor, they were able to create the first white LED, breaking definitively into the illumination applications.

Today LEDs has reached high levels of performance that really have gone beyond any initial expectations. Actually LEDs systems are available and suitable for almost any kind of lighting applications, included floodlighting and far distance lighting, even up to more than 100 meters. In recent laboratory tests white LEDs have achieved performance of over 100 lumen per watt, making them ideal for relevant energy saving illumination applications.

RS Components has immediately understood the high potentiality in the market of LED lamps and is in constant cooperation with the main LED lamp manufacturers and developers, such as Philips Lighting, in order to offer the more wide and up to date LED lighting solutions.