Transient electroluminescence under double voltage pulse: charge accumulation in light-emitting devices based on alizarin violet

Abstract

Transient characteristics of organic light-emitting devices with alizarin violet as emitting material have been studied. A sequence of two voltage pulses separated by a time delay was applied. From the transient response of electroluminescence, the effects of accumulated and injected carriers have been separated out. During the first voltage pulse, the intrinsically accumulated charges generated a peak in luminance, which was absent during the latter pulses. The separation time between the two pulses has been varied to study the relaxation dynamics of the accumulated carriers. By varying the molar concentration of the emitting material, we have studied the parameters related to electron barrier modification and discussed the contribution of accumulated carriers in device operation.