Solid State Luminescence

Historically, black body radiation in the tungsten filament lamp was our primary industrial means for producing 'artificial' light, as it replaced gas lamps. Solid state luminescent devices for applications ranging from lamps to displays have proliferated since then, particularly owing to the develop­ ment of semiconductors and phosphors. Our lighting products are now mostly phosphor based and this 'cold light' is replacing an increasing fraction of tungsten filament lamps. Even light emitting diodes now chal­ lenge such lamps for automotive brake lights. In the area of information displays, cathode ray tube phosphors have proved themselves to be outstandingly efficient light emitters with excellent colour capability. The current push for flat panel displays is quite intense, and much confusion exists as to where development and commercialization will occur most rapidly, but with the need for colour, it is now apparent that solid state luminescence will play a primary role, as gas phase plasma displays do not conveniently permit colour at the high resolution needed today. The long term challenge to develop electroluminescent displays continues, and high performance fluorescent lamps currently illuminate liquid crystal monochrome and colour displays. The development of tri­ component rare earth phosphors is of particular importance.