Luminescence Phenomena

Light emitting plastics is one of the major applications of organic semiconductors. This involves the process of luminescence phenonmena. In order to provide visual information, materials are usually put in conditions that allow them to emit light. Luminescence is the process of light emission by a solid when given some form of energy.

The energy can be provided by a several methods depending on the excitation process. photoluminescence: excitation comes from absorption of photons

cathodoluminescence: phosphor excitation due to bombardment by an electron beam (in old-fashioned displays for TVs and desktop computers)

electroluminescence: excitation due to application of an electric field and injection of charge carriers (electrical current) This is the basis for the new generation of LED and OLED TVs and monitors.

Whatever the source of excitation the final step is an electronic transition between two states of energy E1 and E0 with emission of a photon of a specific wavelength and color that depends on the energy levels.

<math>h\nu = E_1 - E_0 = \frac{hc}{\lambda}\,\!</math>