Anthracene crystals electroluminescence

Electroluminescence from organic materials was first discovered using solid anthracene crystals immersed in a liquid electrolyte. " Very high voltages, e.g. 400-2000 V, were necessary in order to observe electroluminescence partly due... 

The electroluminescence was located in the part of the anthracene crystal next to the hole-injecting anode, which suggests an imbalance of charge-carrier injection and transport. The intensity of light was linearly proportional to the... 

The phenomenon of electroluminescence in organic soUds has been known since the 1960 s at that time. Pope et al. [1] and Helfrich and Schneider [2] discovered and investigated the electroluminescence of anthracene crystals between two electrodes, an anode and a cathode. The thickness of the highly-purified anthracene crystal platelets was large in these first experiments 10-20 /wm or 1-5 mm. The two electrodes on the surfaces of the crystal platelets were silver paste or liquid, highly concentrated solutions of NaCl. The necessary external voltages varied between 50 and 2000 V. Later, Williams and Schadt [3] were the first to construct a display , likewise from anthracene crystals, but with solid, laterally-structured electrodes, and they encapsulated it to prevent its degradation in the air. 

The first observations of electroluminescence from organic materials were made in the 1950s [1]. Interest in this phenomenon was fueled by the work of Pope et al. [2], who observed electroluminescence from single crystals of anthracene. A voltage was applied between silver paste electrodes that were placed on the opposite sides of an anthracene... 

Ordered conjugated organic materials exhibit low trap densities and high charge carrier mobilities, for both electrons and holes. As an example, in single crystals of anthracene [87], the hole and electron mobilities are approximately 1 cm V s and the crystal photoluminescence quantum yield at room temperature is almost unity. Both electroluminescence [87] and stimulated emission... 

Electroluminescence is the emission of light by electrical excitation. Pope and co-workers [212] observed emission in single crystals of anthracene using silver paste electrodes at 400 V. Subsequently, it was established that the phenomenon of electroluminescence necessitates the injection of electrons from one electrode and holes from the other, the capture of one by the other (recombination) and the radioactive decay of the excited state (exciton) produced by the recombination process. 

Another recent discovery of the interaction of polymers with electricity involves polymers that emit fight. Electroluminescence, EL, the generation of fight by electrical excitation, is a phenomenon that has been seen in a wide range of semiconductors. It was first reported for anthracene singe crystals in the 1960s. The basic phenomenon requires the injection of electrons from one electrode and holes (i.e., the withdrawal of electrons) from the other, followed by the capture of the now oppositely charged carriers by recombination. This capture produces a radiative decay of the excited electron-hole state produced by this recombination process (76). 

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