Development of inverted OLED with top ITO anode by plasma damage-free sputtering

Abstract

A newly-developed damage-free sputtering system, Hyper-thermal Neutral Beam (HNB) sputtering, was evaluated for the production of organic light emitting diode (OLED) devices. An indium tin oxide (ITO) pixel layer as an anode electrode was deposited directly on the Hole Transport Layer (HIL) of an Inverted Bottom emission OLED (IBOLED) structure. Two types of IBOLED devices were fabricated to assess the level of process damage by the HNB sputtering deposition process. The characteristics of the leakage current at reverse bias and the UV exposure test confirmed that HNB ITO sputtering does not damage the underlying organic layers in the IBOLED device with the top ITO anode deposited by HNB sputtering, which is in comparison with a normal IBOLED with a top Au anode deposited by conventional thermal evaporation. However, the IBOLED device using HNB sputtering process showed some degradation of the turn-on characteristics and current efficiency. This degradation was not induced by damage from the HNB sputtering process but was generated by the permeation of Fe impurities from the stainless steel chamber and the low conductivity of HNB sputtered ITO thin film. (C) 2009 Elsevier B.V. All rights reserved.