Electroluminescence

SOLIDS CAN GENERATE visible light in several ways. A solid raised to sufficiently high temperature, for example, will emit light, a principle that is used in the tungsten incandescent lamp. But practical considerations limit the efficiency and reliability of such a lamp. In electroluminescence, however, electronic energy can be converted directly into light, and in principle, there is nothing to prevent this process from being very efficient in a simple rugged device operating at room temperature (figures 1–3). Needless to say, such a possibility has aroused much curiosity.