Enhanced Performance of an Organic Light-Emitting Device by Using an Oxidant Component during a Surface Reaction Process by Using Atomic Layer Chemical Vapor Deposition

Abstract

We studied the use of a tetrakis(ethylmethylamino)hafnium(TEMAH, Hf[N(CH(3))C(2)H(5)](4)) precursor with atomic layer chemical vapor deposition (ALCVD) to improve the performance of organic light-emitting diodes (OLEDs). In order to find the optimum condition, we investigated the HfC(x), HfO(x) and HfO(2) treatments to discover how the oxidant components during the surface reaction process influenced the OLED performance. The OLEDs with 5 cycles of HfO(x) treatment reduced the turn-on voltage (similar to 3.5 V) and increased the ITO work function compared to the values for OLEDs modified 1)), using a HfC(x) reactant, without an oxidant. The formation of Hf-O bonding with a high dipole moment on ITO appears to cause the work function shift and a subsequent bias-induced realignment of the anode Fermi level with the highest occupied molecular orbital of the hole transport layer.