Emission behavior of electroluminescent device using a liquid crystal and an electrolyte

In order to lower the operating voltage of molecularly doped electroluminescent (EL) devices using a low-molecular-weight liquid crystal (LC), we added a small amount of electrolytes (tetrabutylammonium bromide: TBAB) to the EL devices. The addition of TBAB decreased the driving voltages by one order of magnitude. Furthermore, the EL devices containing TBAB could be operated under not only a dc mode but also an ac mode. It has become apparent that the emission intensity increases in the order of smectic A phase < nematic phase = isotropic phase, suggesting that the emission intensity is closely related to the viscosity of the LC phase and mobility of the electrolyte.