Low-cost zinc complexes for white organic light-emitting devices

A series of blue fluorescent Zn (II) tetradentate Schiff base complexes has been designed and synthesized for applications in organic light-emitting diodes. The five complexes were investigated as dopant materials or as single emitters of multilayered p-i OLEDs. White OLEDs were achieved using these compounds as dopants of 4,4′,4″-tris(N-carbazolyl)triphenylamine and best devices exhibited a high quality white-light emission with remarkable CIE (Commission Internationale de l'Eclairage) coordinates (0.33, 0.34). When used as single emitters, sky-blue and blue electroluminescent devices were prepared, except with one complex that gave yellow OLEDs. Optical properties of these complexes were examined by UV-visible absorption and luminescence spectroscopy. Their electrochemical properties are also reported. These results open the route to the development of cost-effective complexes for white organic light-emitting devices applications.