Light-emitting diode into a lower energy level and releases energy in the form of a photon. The wavelength of the light emitted, and thus its color, depends on the band gap energy of the materials forming the "p-n junction". In silicon or germanium diodes, the electrons and holes usually recombine by a "non-radiative transition", which produces no optical emission, because these are indirect band gap materials. The materials used for the LED have a direct band gap with energies corresponding to near-infrared, visible, or near-ultraviolet light. LED development began with infrared and red devices made with gallium arsenide. Advances in materials science
LED street light Such street lights can also cause glare for drivers and pedestrians. A drawback of LED focus panels is that most light is directed to the road, and less light to the footpaths and other areas. This can be addressed by the use of specialized lens design and adjustable mounting spigots. In performing a LED street lighting project, easy LED luminary models simplify the optimization for high-performance illumination designs. These practical equations may be used to optimize LED street lighting installations in order to minimize light pollution, increase comfort and visibility, and maximize both illumination uniformity and light utilization efficiency. The