Effect of anode surface treatment by oblique ion bombardment method on organic light-emitting diodes performance

Abstract

In this work, The influence of oblique ion bombardment treatment of the surface of indium tin oxide (ITO) thin films, on the surface parameters of the film and then the performance of organic light-emitting diodes (OLEDs) has been investigated. Both commercially available and uniquely fabricated ITO substrates which were deposited by electron beam evaporation method have been employed. The ITO surface characteristics have been investigated by atomic force microscopy (AFM), X ray diffraction (XRD) and UV-Vis-NIR spectrophotometer. Then a typical OLED device was fabricated on different ITO surfaces and characterized by Keitley 2450 and JAZ spectrometer. The results show that after anode surface treatment by means of oblique Argon ion bombardment method, surface roughness is extremely decreased, which resulted in increasing current and power efficiencies and also there was no evidence of ohmic junctions before driving voltage. The maximum ohmic resistance, current and power efficiencies were 371 MΩ, 6.4 cd/A and 0.91 cd/w, respectively. Also it is found that local non-emissive area or dark spots creation reduced for treated surface device. These findings provide a simple way to effectively reduce the roughness of the ITO films as anode to be applied in optoelectronic devices such as OLEDs. © 2019 Elsevier B.V.