Effects of interfacial stability between electron transporting layer and cathode on the degradation process of organic light-emitting diodes

Abstract

The authors have demonstrated that the increase of electron injection barrier height between tris(8-hydroxyquinoline)aluminum ( Al q 3 ) and Li F ∕ Al cathode is one of the most critical parameters to determine the reliability of organic light-emitting diode with the typical structure of indium tin oxide/ N , N ′ -bis(naphthalen-1-yl)- N , N ′ -bis(phenyl) benzidine/ Al q 3 ∕ Li F ∕ Al . The electrical properties of several devices (hole only, electron only, and integrated double-layered devices) have been measured in the function of operating time to analyze the bulk and interface property changes. Bulk properties of trap energy and mobility in an organic layer have been estimated by using trap-charge-limited currents and transient electroluminescence measurements.