A facile synthesis and optoelectronic characterization of Znq2 and Alq3 nano-complexes

We prepared two organo-metallic nano-complexes zinc bis(8-hydroxyquinoline)(Znq2) and aluminum tris(8-hydroxyquinoline)(Alq3), and utilized these materials as fluorescent part in organic light-emitting diodes (OLEDs). The nano-complexes were synthesized via a facile and rapid chemical method and were characterized by scanning electron microscopy, X-ray diffraction, ultraviolet–visible, Fourier transform infrared spectroscopy, and Photoluminescence spectroscopy. The energy levels of Zn and Al complexes were determined by cyclic voltammetry measurements. Further structural elucidation was carried out using FT-IR in which the stretching frequencies of the Znq2 and Alq3 bonds were determined. Green photoluminescence with maximums at 565 and 524 nm was observed from the Znq2 and Alq3 powders, respectively. In comparison to Alq3 complex the photoluminescence intensity of Znq2 complex is less. In this work, we also investigate electrical and optical performance of the organic light-emitting diodes with both zinc and aluminum complexes as emissive materials. For this purpose we prepared four sets of samples. We configured the samples into two structures: (A) indium tin oxide(ITO)/poly(3,4-ethylenedi-oxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/polyvinylcarbazole(PVK)/Alq3 or Znq2/(2-4-biphenylyl)-5-phenyl-oxadiazole(PBD)/aluminum(Al) and at the second structure (B) ITO/PEDOT:PSS/PVK: Alq3 or Znq2: PBD/Al was prepared. Hole transport layer (HTL), electron transport layer (ETL), and emissive layers were deposited by the spin-coating method, and cathode layer (Al) was also deposited by the thermal evaporation method. Our results show that the electrical efficiency of zinc complex-based devices is much better than Alq3-based devices.