In previous papers, we introduced a novel analysis technique of the impedance spectroscopy of organic light emitting diodes to elucidate their layer-to-layer carrier dynamics and proposed a novel carrier transport model. In this article, we will discuss the carrier dynamics in the voltage region where the layer-to-layer dynamics cannot be distinguished. There appear several specific characteristic features in frequency- and voltage-dependence of complex impedance, the negative impedance, and the diffusion impedance. In the negative bias voltage region, where neither carrier injection nor accumulation occurs, conductance shows omega(1/2) frequency dependence. On the other hand, at the higher voltage region where all the semicircles in Cole-Cole plot coalesce, there appear two types of negative impedance, which have omega(1/2) and a Debye-like frequency dependence. We consider that the omega(1/2) dependences are attributed to the diffusion impedance (Warburg impedance) coupled with and without the interfacial charge transfer reaction. The Debye-like negative impedance is attributed to the carrier trap at the interface of the Alq(3) layer.
Related
Batch download
Cited By
noting
Similar Literature
Submit Feedback
Please wait while the file you selected is being converted