Development and characterization of light-emitting diodes (LEDs) based on ruthenium complex single layer for transparent displays

Abstract

In this work, two ruthenium complexes, [Ru(bpy)3](PF 6)2 and [Ru(ph2phen)3](PF6) 2 in poly(methylmethacrylate) matrix were employed to build single-layer light-emitting electrochemical cells by spin coating on indium tin oxide substrate. In both cases the electroluminescence spectra exhibit a relatively broad band with maxima near to 625 nm and CIE (x, y) color coordinates of (0.64, 0.36), which are comparable with the photoluminescence data in the same medium. The best result was obtained with the [Ru(bpy) 3](PF6)2 device where the optical output power approaches 10 μW at the band maximum with a wall-plug efficiency higher than 0.03%. The lowest driving voltage is about 4 V for an electrical current of 20 mA.