Nanotechnology for solid-state lighting

Lighting has evolved over the last 150 years from the primordial use of fire, incandescence from filaments, to fluorescence and electrical discharge in gases. The use of each new material has led to the improvement in luminous efficacy by an order of magnitude. The incandescent light bulb, invented by Edison in 1879, will be phased out over the next few years as governments sought to ban its manufacture and use because of its low efficiency (< 5%) and to introduce green technology. The fluorescent lamp, which is widely used to replace the incandescent bulb with its use of mercury and presence of lead in some phosphors, is seen as an interim measure.