Electroluminescence and Charge Carrier Transport in Potassium-Doped Anthracene

The increase in the electroluminescence (EL) intensity in potassium-doped anthracene crystals (K-Ant) was investigated in relation to the mechanism of EL. Carrier drift mobilities µe+h and transient EL were measured by the doubly-injected impulse method. The drift mobility of K-Ant along the c'-axis was larger by a factor of 1.5 than in an undoped anthracene single crystal for electric fields larger than 1.9×104V·cm-1. An analysis of the transient EL showed that recombination through recombination centers in K-Ant crystals occurs more efficiently than in anthracene single crystals. These results reveal that the potassium atoms in K-Ant crystals do not act as carrier traps but, rather, act as recombination centers.