Electroluminescence, definition

Luminescence covers all emissions of light in the near IR, VIS and near UV spectral regions. The origin of the luminescence can be specified as photoluminescence , electroluminescence , chemiluminescence , or bioluminescence for example. These definitions depend on the mode of formation of the excited molecule which eventually emits the luminescence. 

A patent is issued for the Indiglo nightlight, consisting of electroluminescent phosphor particles High-definition television is invented... 

The importance of these amorphous layers derives from their electronic structure. There are no longer sharp bands characterized by a definite band gap, but quasi-continuous changes in the density of states are observed leading to differences between the optical gap and the mobility gap . Thus, interesting optoelectronic properties and applications are reported, e.g., photoconductivity and solar cells [204, 205], optical vnndows for solar cells [206, 207], electroluminescence and light emitting diodes (LED) [207, 208], or thermistors for IR sensors [209]. 

Different two layer light emitting diodes (LEDs) have been tested using the aromatic oxadiazole polymers as electron transporting layer, with PPV as emissive layer. It was found that the use of the aromatic oxadiazole polymers can realise efficient light emission using stable aluminum metal as cathode. No definite enhancement of electroluminescence efficiency has yet been observed. This can probably be explained by the fact that PPV and the oxadiazole polymers 18-20 have similar reduction potentials, and therefore by analogy similar LLMO levels. 

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