LED is the acronym of “Light Emitting Diode”. In its turn, diode is a word composed of two terms, di meaning two and ode from electrode.
Therefore, as far as physics is concerned, LED is a special kind of positive/negative junction diode (P-N), composed of a thin layer of semiconductor.
The main feature of said device is that current passes through it in only one direction, blocking any current flowing in the opposite. The basic principle on which it operates is called “electroluminescence”, i.e., the emission of photons generated by the recombination of electrons and holes when the junction is polarised directly.
The very first LED ever invented dates back to 1962 by Nick Holonyack Jr., but research have gone on since then and thanks to this extraordinary technology I. Akasaki, H. Amanoe and S. Nakamura were awarded the Nobel prize for physics in 2014 for their studies on blue light LED.
The revolutionary scope of this device has then become apparent. What stands out is the relation between the quantity of emitted light and consumption, calculated as a 3 to 1 ratio, but it keeps on increasing thanks to new findings. Energy saving is tangible and not at all secondary as our times impose a rational use of energy sources and technologies aimed at preventing wastes. 36% of yearly CO² emissions in Europe are due to energy use in residential buildings, which could be dramatically cut by LED devices. This awareness has become the rationale of the 2009 EC ban on incandescence bulbs.
Energy saving, environmental friendliness and drop in energy bills - about – 65 to 70%. This is so true that a number of municipalities decided to opt for LED devices in public lighting.