Conduction in aluminum(III) 8-hydroxyquinoline (Alq3) was modeled based on trap-charge limited conduction of electrons in the bulk. The evolution of a narrow Gaussian distribution of localized trap states below the lowest unoccupied molecular orbital (LUMO) of Alq3,
lying against a natural exponential background, was used to explain changes in the current-voltage characteristic and external quantum efficiency with time observed by many researchers for organic light-emitting diodes. Based on the change of the shape of the
Keith A. Higginson, Mathew K. Mathai, Faquir Jain, Fotios Papadimitrakopoulos, Bing R. Hsieh, "Chemical Aging, Charge Transport, and Electroluminescence in Alq3-based Organic Light-Emitting Diodes" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP16), 2000, pp 354 - 357, https://doi.org/10.2352/ISSN.2169-4451.2000.16.1.art00093_1