Fabrication and characterization of zinc oxide nanoflower-based electrochemical luminescence cells

In this paper, we report characteristics of electrochemical luminescence (ECL) cells having zinc oxide nanoflower (ZnO NF) layer as an electrode. The characteristics of ZnO NF can be used in electron excitation transfer on Ru(II) complex [Ru(bpy)32+]. The ZnO NF-based ECL cell has a simple structure, which is composed of a ZnO NF layer and Ru(II) complex between fluorine doped tin oxide (FTO) glasses. In order to characterize the structural properties of ZnO NF, X-ray diffraction (XRD) and scanning electron microscope (SEM) were used. The effect of thickness ZnO NF on emissive and opto-electrical properties of ECL cells was investigated. Thicknesses of ZnO NF ranging from 1 μm to 7.5 μm were used in this work. The luminescence spectrum of the emission from ECL cell with different thickness of ZnO NF was measured and the central wavelength of luminescence was located at 620 nm. For characterization of optical and electrical properties of ECL cells with ZnO NF, luminance and driving current was measured and ECL efficiency was calculated at different operating voltages. The optimum thickness of the ZnO NF was found at 5 μm where it improves opto-electrical characteristics of ECL cell. At an operating voltage of 3 V and a frequency of 60 Hz, the highest luminance of 154 cd/m2 and ECL efficiency of 0.456 lm/W were obtained from ECL cell with ZnO NF thickness of 5 μm.