Investigation on Al(III) and Zn(II) complexes containing a calix[4]arene bearing two 8-oxyquinoline pendant arms used as emitting materials for OLEDs

A comparison between [Al·1]3+ and [Zn·1]2+ complexes (1 = 5,11,17,23-tetra-tert-butyl-25,27-bis[(quinoline-8-oxy)propyloxy]-26, 28-dihydroxy-calix[4]arene) has been made using electrochemical techniques and the experimental results obtained in the fabrication of organic light emitting devices (OLEDs). The electrochemically determined values of the ionization potential Ip and electron affinity Ea parameters for the [Al·1]3+ (Ip = 5.82eV, Ea = 2.80eV) and [Zn·1]2+ (Ip = 5.67eV, Ea = 2.32eV) evidenced that the [Al·1]3+ complex is a better electron transporting layer with respect to the Zn complex one. The fabricated OLEDs based on these supramolecular complexes show a superior quality with the [Al·1]3+ systems expected from the energy level diagrams