Light- and ion-gauge-induced space charges in tris-(8-hydroxyquinolate) aluminum-based organic light-emitting diodes

Noguchi, Yutaka; Sato, Naoki; Miyazaki, Yukimasa; Ishii, Hisao
April 2010
Applied Physics Letters;4/5/2010, Vol. 96 Issue 14, p143305
Academic Journal
We report space charge formation in tris-(8-hydroxyquinolate) aluminum (Alq3)-based organic light-emitting diodes induced by light irradiation and ion-gauge (IG) operation during device fabrication. An analysis of the capacitance-voltage curves of the light-treated devices reveals the presence of uniformly distributed negative space charges in the Alq3 layer. Spatial inhomogeneity of the orientation polarization as well as electrons trapped in the Alq3 film can be the origin of the negative space charge. We also found that positively charged species can be included in the device due to IG operation.


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